To investigate the microstructure and creep properties of a hot corrosion resistant Ni-based single crystal superal oy containing different hafnium(Hf)additions(0-0.4wt.%),creep test was performed at 980℃/200 MPa.Opt...To investigate the microstructure and creep properties of a hot corrosion resistant Ni-based single crystal superal oy containing different hafnium(Hf)additions(0-0.4wt.%),creep test was performed at 980℃/200 MPa.Optical microscopy,scanning electron microscopy,electron probe micro analysis(EPMA),and transmission electron microscopy were employed to analyze the microstructure differences.With the increase of Hf,the creep rupture life of the alloys at 980℃/200 MPa gradually increases.Microstructure analysis reveals that Hf promotes the transformation of carbide morphology from script to rod-like and finally to blocky.Upon the addition of Hf,there is an increase in the volume fraction of blocky MC carbides,along with an elevation in the partitioning ratio of Cr and Mo elements.Concurrently,theγ/γ′interfacial dislocation spacing undergoes a reduction.It is found that script carbides are more likely to cause stress concentration in high temperature creep,leading to nucleation and propagation of microcracks.The formation mechanism of blocky MC carbides is related to the increase in precipitation temperature and lattice constant,and its beneficial impact on creep resistance is also investigated based on the analysis of the creep test results.展开更多
The effect of Mg/Si mass ratio on the microstructure and mechanical properties of Al-Mg-Si cast aluminum alloys under sub-rapid solidification conditions was investigated.This study utilized four different Mg/Si ratio...The effect of Mg/Si mass ratio on the microstructure and mechanical properties of Al-Mg-Si cast aluminum alloys under sub-rapid solidification conditions was investigated.This study utilized four different Mg/Si ratios:2.83,1.91,1.73,and 1.53.To analyze the evolution of the microstructure,particularly the second phase,various techniques were employed:optical microscopy(OM),scanning electron microscopy(SEM),energy dispersive spectrometry(EDS),and electron backscatter diffraction(EBSD).Additionally,thermodynamic calculations were performed using the Thermal-calc software to further understand the microstructural changes.Results show that as the Mg/Si ratio decreases from 2.83 to 1.53,α-Al grains become more uniformly distributed.Meanwhile,the morphology of the Mg_(2)Si phases changes from skeletal to short stick shapes with a decreasing aspect ratio.An as-cast Al-Mg-Si alloy with a Mg/Si ratio of 1.53 exhibits high strength,achieving an ultimate tensile strength(UTS)of 320.6 MPa and a yield strength(YS)of 249.9 MPa.The cast alloy with a Mg/Si ratio of 2.83exhibits the highest elongation,reaching 5.31%.This superior elongation is attributed to the uniform distribution of Mg_(2)Si phases,which possess a long skeletal shape.Conversely,the alloy with a Mg/Si ratio of 1.53 demonstrates the lowest elongation,primarily due to the central concentration of Mg_(2)Si phases,which are characterized by their short stick shapes.展开更多
Erratum to:International Journal of Minerals,Metallurgy and Materials Volume 31,Number 11,November 2024,Page 2498 https://doi.org/10.1007/s12613-024-2847-2 In this article,the fund number in the acknowledgements has b...Erratum to:International Journal of Minerals,Metallurgy and Materials Volume 31,Number 11,November 2024,Page 2498 https://doi.org/10.1007/s12613-024-2847-2 In this article,the fund number in the acknowledgements has been erroneously given as the Program for Guangdong Basic and Applied Basic Research Foundation,China(No.2021A151511006)It should be as follows:the Program for Guangdong Basic and Applied Basic Research Foundation,China(No.2021A1515110061).展开更多
Thermal barrier coatings(TBCs)can effectively protect the alloy substrate of hot components in aeroengines or land-based gas turbines by the thermal insulation and corrosion/erosion resistance of the ceramic top coat....Thermal barrier coatings(TBCs)can effectively protect the alloy substrate of hot components in aeroengines or land-based gas turbines by the thermal insulation and corrosion/erosion resistance of the ceramic top coat.However,the continuous pursuit of a higher operating temperature leads to degradation,delamination,and premature failure of the top coat.Both new ceramic materials and new coating structures must be developed to meet the demand for future advanced TBC systems.In this paper,the latest progress of some new ceramic materials is first reviewed.Then,a comprehensive spalling mechanism of the ceramic top coat is summarized to understand the dependence of lifetime on various factors such as oxidation scale growth,ceramic sintering,erosion,and calcium–magnesium–aluminium–silicate(CMAS)molten salt corrosion.Finally,new structural design methods for high-performance TBCs are discussed from the perspectives of lamellar,columnar,and nanostructure inclusions.The latest developments of ceramic top coat will be presented in terms of material selection,structural design,and failure mechanism,and the comprehensive guidance will be provided for the development of next-generation advanced TBCs with higher temperature resistance,better thermal insulation,and longer lifetime.展开更多
During aircraft,ship,and automobile manufacturing,lap structures are frequently produced among Al alloy skins,wall panels,and stiffeners.The occurrence of welding defects severely decreases mechanical properties durin...During aircraft,ship,and automobile manufacturing,lap structures are frequently produced among Al alloy skins,wall panels,and stiffeners.The occurrence of welding defects severely decreases mechanical properties during friction stir lap welding(FSLW).This study focuses on investigating the effects of rotation rate,multipass welding,and cooling methods on lap defect formation,microstructural evolution,and mechanical properties.Hook defects were eliminated by decreasing welding speed,applying two-pass FLSW with a small welding tool,and introducing additional water cooling,thus leading to a remarkable increase in effective sheet thickness and lap width.This above strategy yielded defect-free joints with an ultrafine-grained microstructure and increased tensile shear force from 298 to 551 N/mm.The fracture behavior of FSLW joints was systematically studied,and a fracture factor of lap joints was proposed to predict their fracture mode.By reducing the rotation rate,using two-pass welding,and employing additional water cooling strategies,an enlarged,strengthened,and defect-free lap zone with refined ultrafine grains was achieved with a quality comparable to that of lap welds based on 7xxx Al alloys.Importantly,this study provides a valuable FSLW method for eliminating hook defects and improving joint performance.展开更多
Despite transosseous rotator cuff tear repair using sutures is widely accepted for tendon-bone fixation,the fibrocartilaginous enthesis regeneration is still hardly achieved with the traditional sutures.In the present...Despite transosseous rotator cuff tear repair using sutures is widely accepted for tendon-bone fixation,the fibrocartilaginous enthesis regeneration is still hardly achieved with the traditional sutures.In the present work,degradable magnesium(Mg)alloy wire was applied to suture supraspinatus tendon in a rat acute rotator cuff tear model with Vicryl Plus 4±0 absorbable suture as control.The shoulder joint humerus-supraspinatus tendon complex specimens were retrieved at 4,8,and 12 weeks after operation.The Mg alloy suture groups showed better biomechanical properties in terms of ultimate load to failure.Gross observation showed that hyperplastic response of the scar tissue at the tendon-bone interface is progressively alleviated over time in the both Mg alloy suture and Vicryl suture groups.In the histological analysis,for Mg alloy suture groups,chondrocytes appear to proliferate at 4 weeks postoperatively,and the tendon-bone interface showed an orderly structural transition zone at 8 weeks postoperatively.The collagenous fiber tended to be aligned and the tendon-bone interlocking structures apparently formed,where transitional structure from unmineralized fibrocartilage to mineralized fibrocartilage was closer to the native fibrocartilaginous enthesis.In vivo degradation of the magnesium alloy wire was completed within 12 weeks.The results indicated that Mg alloy wire was promising as degradable suture with the potential to promotes fibrocartilaginous interface regeneration in rotator cuff repair.展开更多
A high-zinc composite,12vol%SiC/Al-13.3 Zn-3.27 Mg-1.07Cu(wt%),with an ultra-high-strength of 781 MPa was success-fully fabricated through a powder metallurgy method,followed by an extrusion process.The effects of sol...A high-zinc composite,12vol%SiC/Al-13.3 Zn-3.27 Mg-1.07Cu(wt%),with an ultra-high-strength of 781 MPa was success-fully fabricated through a powder metallurgy method,followed by an extrusion process.The effects of solid-solution and aging heat treat-ments on the microstructure and mechanical properties of the composite were extensively investigated.Compared with a single-stage sol-id-solution treatment,a two-stage solid-solution treatment(470℃/1 h+480℃/1 h)exhibited a more effective solid-solution strengthen-ing owing to the higher degree of solid-solution and a more uniform microstructure.According to the aging hardness curves of the com-posite,the optimized aging parameter(100℃/22 h)was determined.Reducing the aging temperature and time resulted in finer and more uniform nanoscale precipitates but only yielded a marginal increase in tensile strength.The fractography analysis revealed that intergranu-lar cracking and interface debonding were the main fracture mechanisms in the ultra-high-strength SiC/Al-Zn-Mg-Cu composites.Weak regions,such as the SiC/Al interface containing numerous compounds and the precipitate-free zones at the high-angle grain boundaries,were identified as significant factors limiting the strength enhancement of the composite.Interfacial compounds,including MgO,MgZn2,and Cu5Zn8,reduced the interfacial bonding strength,leading to interfacial debonding.展开更多
The basal texture of traditional magnesium alloy AZ31 is easy to form and exhibits poor plasticity at room temperature.To address these problems,a multi-micro-alloyed high-plasticity Mg-1.8Zn-0.8Gd-0.1Ca-0.2Mn(wt%)all...The basal texture of traditional magnesium alloy AZ31 is easy to form and exhibits poor plasticity at room temperature.To address these problems,a multi-micro-alloyed high-plasticity Mg-1.8Zn-0.8Gd-0.1Ca-0.2Mn(wt%)alloy was developed using the unique role of rare earth and Ca solute atoms.In addition,the influence of the annealing process on the grain size,second phase,texture,and mechanical properties of the warm-rolled sheet at room temperature was analyzed with the goal of developing high-plasticity mag-nesium alloy sheets and obtaining optimal thermal-mechanical treatment parameters.The results show that the annealing temperature has a significant effect on the microstructure and properties due to the low alloying content:there are small amounts of larger-sized block and long string phases along the rolling direction(RD),as well as several spherical and rodlike particle phases inside the grains.With increas-ing annealing temperature,the grain size decreases and then increases,and the morphology,number,and size of the second phase also change correspondingly.The particle phase within the grains vanishes at 450℃,and the grain size increases sharply.In the full recrystal-lization stage at 300-350℃,the optimum strength-plasticity comprehensive mechanical properties are presented,with yield strengths of 182.1 and 176.9 MPa,tensile strengths of 271.1 and 275.8 MPa in the RD and transverse direction(TD),and elongation values of 27.4%and 32.3%,respectively.Moreover,there are still some larger-sized phases in the alloy that influence its mechanical properties,which offers room for improvement.展开更多
Compared with the conventional Charpy impact test method,the oscillographic impact test can help in the behavioral analysis of materials during the fracture process.In this study,the trade-off relationship between the...Compared with the conventional Charpy impact test method,the oscillographic impact test can help in the behavioral analysis of materials during the fracture process.In this study,the trade-off relationship between the strength and toughness of a DZ2 axle steel at various tempering temperatures and the cause of the improvement in impact toughness was evaluated.The tempering process dramatically influenced carbide precipitation behavior,which resulted in different aspect ratios of carbides.Impact toughness improved along with the rise in tempering temperature mainly due to the increase in energy required in impact crack propagation.The characteristics of the impact crack propagation process were studied through a comprehensive analysis of stress distribution,oscilloscopic impact statistics,fracture morphology,and carbide morphology.The poor impact toughness of low-tempering-temperature specimens was attributed to the increased number of stress concentration points caused by carbide morphology in the small plastic zone during the propagation process,which resulted in a mixed distribution of brittle and ductile fractures on the fracture surface.展开更多
The tungsten fibers or powders reinforced Zr_(52)Cu_(32)Ni_(6)Al_(10),(Zr_(52)Cu_(32)Ni_(6)Al_(10))_(98)Nb_(2),and(Zr_(52)Cu_(32)Ni_(6)Al_(10))_(98)Be_(2)bulk metallic glass composites(BMGCs)were fabricated using the ...The tungsten fibers or powders reinforced Zr_(52)Cu_(32)Ni_(6)Al_(10),(Zr_(52)Cu_(32)Ni_(6)Al_(10))_(98)Nb_(2),and(Zr_(52)Cu_(32)Ni_(6)Al_(10))_(98)Be_(2)bulk metallic glass composites(BMGCs)were fabricated using the infiltration casting method.In this study,the wettability between the amorphous alloy melts and tungsten substrates was investigated using the sessile drop method,revealing excellent wettability at 1,010℃.Consequently,an infiltration temperature of 1,010°C was chosen for composite material fabrication.Structural characterization and mechanical property test of both composites were conducted through scanning electron microscopy(SEM),and X-ray diffraction(XRD),and universal mechanical testing.Both tungsten fiber or tungsten powder reinforced Zr_(52)Cu_(32)Ni_(6)Al_(10)and(Zr_(52)Cu_(32)Ni_(6)Al_(10))_(98)Be_(2)composites exhibit the formation of W-Zr phase.In contrast,the tungsten fiber or tungsten powder reinforced(Zr_(52)Cu_(32)Ni_(6)Al_(10))_(98)Nb_(2)composites does not show the formation of W-Zr phase.X-ray diffraction patterns confirm the presence of W reinforcement phases in both composites.The successful fabrication of both composites is evidenced by their remarkable mechanical properties under room temperature compression.The yield strength of all the three tungsten fiber-reinforced composite sample exceeds 2,400 MPa,with the plastic strain exceeding 3.9%,while the yield strength of all the three tungsten powder-reinforced composite sample surpasses 2,700 MPa,with the plastic strain exceeding 30%.Fracture analysis reveals longitudinal splitting in the tungsten fiber-reinforced composites,contrasting with brittle fracture in the tungsten powder-reinforced composites.The denser the shear bands on the amorphous matrix of the two types of composite materials,the better their mechanical properties.展开更多
The low-cycle fatigue behavior of solutionized(T4)and aged(T6)WE43 magnesium alloys was studied at room temperature.The total strain amplitudes(△ε_(t)/2)were 0.4%,0.5%,0.6%,0.7%and 1.0%.Detailed microstructure evolu...The low-cycle fatigue behavior of solutionized(T4)and aged(T6)WE43 magnesium alloys was studied at room temperature.The total strain amplitudes(△ε_(t)/2)were 0.4%,0.5%,0.6%,0.7%and 1.0%.Detailed microstructure evolution was characterized by scanning electron microscope(SEM),electron backscattered diffraction(EBSD)and transmission electron microscopy(TEM).The results showed that plastic strain amplitude decreased with the increasing cycle number in T4 alloy,which is due to the dense persistent slip bands(PSBs)and dynamic precipitates hinderingdislocation slip.In contrast,the plastic strain amplitude increases gradually in T6 alloy,which is attributed to the enhanced activation of pyramidal slip.The low-cycle fatigue life of T6 alloy with larger fatigue ductility coefficient is longer than that of T4 alloy.The Coffin-Manson model can accurately predict the fatigue life of T4 and T6 alloys compared to Jahed-Varvani(JV)energy model.For T4 alloy,the fatigue damage mechanism was dominated by basal slip.For T6 alloy,the enhanced pyramidal slip plays an important role to accommodate plastic deformation.展开更多
The infiltration casting method is widely employed for the preparation of ex-situ composite materials.However,the production of composite materials using this method must necessitates a comprehensive understanding of ...The infiltration casting method is widely employed for the preparation of ex-situ composite materials.However,the production of composite materials using this method must necessitates a comprehensive understanding of the wettability and interface characteristics between the reinforcing phase and the bulk metallic glasses(BMGs).This work optimized the composition of Zr-based BMGs through microalloying methods,resulting in a new set of Zr-based BMGs with excellent glass-forming ability.Wetting experiments between the Zr-based BMGs melts and W substrates were conducted using the traditional sessile drop method,and the interfaces were characterized utilizing a scanning electron microscope(SEM)equipped with energy dispersive X-ray spectroscopy(EDS).The work demonstrates that the microalloying method substantially enhances the wettability of the Zr-based BMGs melt.Additionally,the incorporation of Nb element impedes the formation of W-Zr phases,but the introduction of Nb element does not alter the extent of interdiffusion between the constituent elements of the amorphous matrix and W element,indicating that the influence of Nb element on the diffusion of individual elements is minute.展开更多
Cracks have consistently been a significant challenge limiting the development of additive manufactured nickel-based superalloys.It is essential to investigate the location of cracks and their forming mechanism.This s...Cracks have consistently been a significant challenge limiting the development of additive manufactured nickel-based superalloys.It is essential to investigate the location of cracks and their forming mechanism.This study extensively examines the impact of solidification process,microstructural evolution,and stress concentration on crack initiation during direct energy deposition(DED).The results emphasize that the crack formation is significantly related to large-angle grain boundaries,rapid cooling rates.Cracks caused by large-angle grain boundaries and a fast-cooling rate predominantly appear near the edge of the deposited samples.Liquation cracks are more likely to form near the top of the deposited sample,due to the presence ofγ/γ'eutectics.The secondary dendritic arm and the carbides in the interdendritic regions can obstruct liquid flow during the final stage of solidification,which results in the formation of solidification cracks and voids.This work paves the way to avoid cracks in nickel-based superalloys fabricated by DED,thereby enhancing the performance of superalloys.展开更多
The authors regret to inform that the whole“Acknowledgements”section is missing due to the composing process of the editing.The“Acknowledgements”information that should be added is as follows.
The design of the loading path is one of the important research contents of the tube hydroforming process.Optimization of loading paths using optimization algorithms has received attention due to the inefficiency of o...The design of the loading path is one of the important research contents of the tube hydroforming process.Optimization of loading paths using optimization algorithms has received attention due to the inefficiency of only finite element optimization.In this paper,the hydroforming process of 5A02 aluminum alloy variable diameter tube was as the research object.Fuzzy control was used to optimize the loading path,and the fuzzy rule base was established based on FEM.The minimum wall thickness and wall thickness reduction rate were determined as input membership functions,and the axial feeds variable value of the next step was used as output membership functions.The results show that the optimized loading path greatly improves the uniformity of wall thickness and the forming effect compared with the linear loading path.The round corner lamination rate of the tube is 91.2%under the fuzzy control optimized loading path,which was increased by 47.1%and 22.6%compared with linear loading Path 1 and Path 2,respectively.Based on the optimized loading path in the experiment,the minimum wall thickness of the variable diameter tube was 1.32 mm and the maximum thinning rate was 12.4%.The experimental results were consistent with the simulation results,which verified the accuracy of fuzzy control.The research results provide a reference for improving the forming quality of thin-walled tubes and plates.展开更多
3%Y_(2)O_(3)p/ZGK200 composites were subjected to unidirectional rolling(UR)and cross rolling(CR)at 400℃and 350℃followed by annealing at 300℃for 1 h.The microstructure,texture and mechanical properties of rolled an...3%Y_(2)O_(3)p/ZGK200 composites were subjected to unidirectional rolling(UR)and cross rolling(CR)at 400℃and 350℃followed by annealing at 300℃for 1 h.The microstructure,texture and mechanical properties of rolled and annealed composites were systematically studied.The rolled composites exhibited a heterogeneous microstructure,consisting of deformed grains elongated along rolling direction(RD)and Y_(2)O_(3)particles bands distributed along RD.After annealing,static recrystallization(SRX)occurred and most deformed grains transformed into equiaxed grains.A non-basal texture with two strong T-texture components was obtained after UR while a non-basal elliptical/circle texture with circle multi-peaks was obtained after CR,indicating that rolling path had great influences on texture of the composites.After annealing process,R-texture component disappeared or weakened,as results,a non-basal texture with double peaks tilting from normal direction(ND)to transverse direction(TD)and a more random non-basal texture with circle multi-peaks were obtained for UR and CR composites,respectively.The yield strength of rolled composites after UR showed obvious anisotropy along RD and TD while a low anisotropic yield strength was obtained after CR.Some Y_(2)O_(3)particles broke during rolling.The fracture of the composites was attributed to the existence of Y_(2)O_(3)clusters and interfacial debonding between particles and matrix during tension,as a result,the ductility was not as superior as matrix alloy.展开更多
The high cost and low efficiency of fatigue tests are bottleneck problem for the anti-fatigue design of metallic materials.For this problem,a theoretical fatigue model is proposed in this study,the possible applicatio...The high cost and low efficiency of fatigue tests are bottleneck problem for the anti-fatigue design of metallic materials.For this problem,a theoretical fatigue model is proposed in this study,the possible applications have also been discussed.Specific results would be introduced in two serial papers,in which the first paper focuses on the model building and the applications on fatigue strength prediction;the second paper put emphasis on the influencing factors of the model parameters and the applications on fatigue strength improvement.In this first paper,a theoretical model is proposed considering both the strength and plastic restrictions of fatigue strength.As the model builds up a brief relationship among yield strength(Y),tensile strength(T)and fatigue strength(F),it is named as the Y-T-F model.Through the verification with fatigue strength data covering various kinds of metallic materials and loading conditions,this Y-T-F model exhibits both generality and accuracy.With the Y-T-F model,the efficient fatigue strength prediction could be conducted by brief linear fitting and calculation,just through yield strength,tensile strength and several known fatigue strength data.Moreover,through its deduced Y-F model,the analytical formula of fatigue strength continuously changing with materials strengthening can be obtained,as well as the maximum value of fatigue strength and corresponding critical yield strength.In summary,the Y-T-F model would be useful for reducing the fatigue tests,thus providing new possibilities on the efficient anti-fatigue design and selection of metallic materials.展开更多
In the first paper,a Y-T-F model was proposed based on the restrictions of both strength and plasticity;the corresponding applications on the fatigue strength prediction have also been discussed.In this second paper,t...In the first paper,a Y-T-F model was proposed based on the restrictions of both strength and plasticity;the corresponding applications on the fatigue strength prediction have also been discussed.In this second paper,the emphasis will be put on the issues of fatigue strength improvement.Based on the primary form of the Y-T-F model,the parameters are further analyzed and quantified,to clarify the influences of various factors on fatigue strength.Firstly,the damage capacity C is proved to be sensitive to the elastic modulus E,which could change with the alloying components and nano-scaled grain boundaries;the increase of E would lead to the increasing C,thus increase the fatigue strength.Secondly,the microstructure characteristic coefficient a,as well as the yield strengthσ_(y) and tensile strengthσ_(b) in the crack initiation region could be influenced by the processing mode,grain size and microstructure uniformity of materials;the change of microstructure characteristics would affect the changing tendency of tensile strength--fatigue strength relation via varying the values of a,σ_(y) andσ_(b).Thirdly,the damage weight coefficientωis found to be a reflection of the fatigue strength declination induced by defects;the defect dimension D,the defect shape correlated stress concentration coefficient Kt,as well as the strengthening level of matrix materialsσ_(b) are all corresponding factors.Quantified correlations between the above parameters and corresponding factors are comprehensively built up,hence obtaining the influences of either a single factor or multiple factors on fatigue strength.This further developed Y-T-F model would be helpful to clarify the direction of fatigue strength improvement,and contribute to the anti-fatigue design optimization of metallic materials.展开更多
Solidification experiments were carried out to investigate the kinetic behaviour of TiB2 particles in Al melt and their effect on the grain refinement of commercially-pure Al.A model was proposed to describe the kinet...Solidification experiments were carried out to investigate the kinetic behaviour of TiB2 particles in Al melt and their effect on the grain refinement of commercially-pure Al.A model was proposed to describe the kinetic behaviour of TiB2 particles during the whole process from the addition of TiB2 to the melt to the freezing of the melt.The results indicate that TiB2 particles are not stable in Al melt.They may dissolve and coarsen during the holding period and grow during the cooling period of the melt.The kinetic behaviour of TiB2 particles in the melt has a great influence on their number density and the grain refinement.Solute Ti addition can suppress the dissolution,Ostwald ripening and growth behaviours of TiB2 particles.展开更多
基金financially supported by the National Key Research and Development Program of China (No.2021YFA1600603)the National Science and Technology Major Project (No.J20191-VI-0010-0124)the National Natural Science Foundation of China (No.52071219)。
文摘To investigate the microstructure and creep properties of a hot corrosion resistant Ni-based single crystal superal oy containing different hafnium(Hf)additions(0-0.4wt.%),creep test was performed at 980℃/200 MPa.Optical microscopy,scanning electron microscopy,electron probe micro analysis(EPMA),and transmission electron microscopy were employed to analyze the microstructure differences.With the increase of Hf,the creep rupture life of the alloys at 980℃/200 MPa gradually increases.Microstructure analysis reveals that Hf promotes the transformation of carbide morphology from script to rod-like and finally to blocky.Upon the addition of Hf,there is an increase in the volume fraction of blocky MC carbides,along with an elevation in the partitioning ratio of Cr and Mo elements.Concurrently,theγ/γ′interfacial dislocation spacing undergoes a reduction.It is found that script carbides are more likely to cause stress concentration in high temperature creep,leading to nucleation and propagation of microcracks.The formation mechanism of blocky MC carbides is related to the increase in precipitation temperature and lattice constant,and its beneficial impact on creep resistance is also investigated based on the analysis of the creep test results.
基金supported by the WQ&UCS (Binzhou)Industrialization Research Institute。
文摘The effect of Mg/Si mass ratio on the microstructure and mechanical properties of Al-Mg-Si cast aluminum alloys under sub-rapid solidification conditions was investigated.This study utilized four different Mg/Si ratios:2.83,1.91,1.73,and 1.53.To analyze the evolution of the microstructure,particularly the second phase,various techniques were employed:optical microscopy(OM),scanning electron microscopy(SEM),energy dispersive spectrometry(EDS),and electron backscatter diffraction(EBSD).Additionally,thermodynamic calculations were performed using the Thermal-calc software to further understand the microstructural changes.Results show that as the Mg/Si ratio decreases from 2.83 to 1.53,α-Al grains become more uniformly distributed.Meanwhile,the morphology of the Mg_(2)Si phases changes from skeletal to short stick shapes with a decreasing aspect ratio.An as-cast Al-Mg-Si alloy with a Mg/Si ratio of 1.53 exhibits high strength,achieving an ultimate tensile strength(UTS)of 320.6 MPa and a yield strength(YS)of 249.9 MPa.The cast alloy with a Mg/Si ratio of 2.83exhibits the highest elongation,reaching 5.31%.This superior elongation is attributed to the uniform distribution of Mg_(2)Si phases,which possess a long skeletal shape.Conversely,the alloy with a Mg/Si ratio of 1.53 demonstrates the lowest elongation,primarily due to the central concentration of Mg_(2)Si phases,which are characterized by their short stick shapes.
文摘Erratum to:International Journal of Minerals,Metallurgy and Materials Volume 31,Number 11,November 2024,Page 2498 https://doi.org/10.1007/s12613-024-2847-2 In this article,the fund number in the acknowledgements has been erroneously given as the Program for Guangdong Basic and Applied Basic Research Foundation,China(No.2021A151511006)It should be as follows:the Program for Guangdong Basic and Applied Basic Research Foundation,China(No.2021A1515110061).
文摘Thermal barrier coatings(TBCs)can effectively protect the alloy substrate of hot components in aeroengines or land-based gas turbines by the thermal insulation and corrosion/erosion resistance of the ceramic top coat.However,the continuous pursuit of a higher operating temperature leads to degradation,delamination,and premature failure of the top coat.Both new ceramic materials and new coating structures must be developed to meet the demand for future advanced TBC systems.In this paper,the latest progress of some new ceramic materials is first reviewed.Then,a comprehensive spalling mechanism of the ceramic top coat is summarized to understand the dependence of lifetime on various factors such as oxidation scale growth,ceramic sintering,erosion,and calcium–magnesium–aluminium–silicate(CMAS)molten salt corrosion.Finally,new structural design methods for high-performance TBCs are discussed from the perspectives of lamellar,columnar,and nanostructure inclusions.The latest developments of ceramic top coat will be presented in terms of material selection,structural design,and failure mechanism,and the comprehensive guidance will be provided for the development of next-generation advanced TBCs with higher temperature resistance,better thermal insulation,and longer lifetime.
基金supported by the National Natural Science Foundation of China(Nos.52305436 and 51975553)the Program for Guangdong Basic and Applied Basic Research Foundation,China(No.2021A151511006)+4 种基金Guangxi Science and Technology Major Program,China(No.AA23023029)Liaoning Natural Science Foundation of China(No.2021-MS-007)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(No.Y2021061)the Bintech-IMR R&D Program(No.GYYJSBU-2022-002)the Institute of Metal Research Innovation Found,China(No.2022-PY11).
文摘During aircraft,ship,and automobile manufacturing,lap structures are frequently produced among Al alloy skins,wall panels,and stiffeners.The occurrence of welding defects severely decreases mechanical properties during friction stir lap welding(FSLW).This study focuses on investigating the effects of rotation rate,multipass welding,and cooling methods on lap defect formation,microstructural evolution,and mechanical properties.Hook defects were eliminated by decreasing welding speed,applying two-pass FLSW with a small welding tool,and introducing additional water cooling,thus leading to a remarkable increase in effective sheet thickness and lap width.This above strategy yielded defect-free joints with an ultrafine-grained microstructure and increased tensile shear force from 298 to 551 N/mm.The fracture behavior of FSLW joints was systematically studied,and a fracture factor of lap joints was proposed to predict their fracture mode.By reducing the rotation rate,using two-pass welding,and employing additional water cooling strategies,an enlarged,strengthened,and defect-free lap zone with refined ultrafine grains was achieved with a quality comparable to that of lap welds based on 7xxx Al alloys.Importantly,this study provides a valuable FSLW method for eliminating hook defects and improving joint performance.
基金the National Key Research and Development Program of China(No.2020YFC1107501)the National Natural Science Foundation of China(No.51971222,51801220)+4 种基金the Natural Science Foundation of Liaoning Province of China(No.2020-MS-001)the Dong Guan Innovative Research Team Program(No.2020607134012)the Military Translational Medicine Fund of Chinese PLA General Hospital(ZH19008)Capital’s Funds for Health Improvement and Research(CFH 2022-2-5051)the Dong Guan Science and Technology Service Network Initiative(20201600200042)。
文摘Despite transosseous rotator cuff tear repair using sutures is widely accepted for tendon-bone fixation,the fibrocartilaginous enthesis regeneration is still hardly achieved with the traditional sutures.In the present work,degradable magnesium(Mg)alloy wire was applied to suture supraspinatus tendon in a rat acute rotator cuff tear model with Vicryl Plus 4±0 absorbable suture as control.The shoulder joint humerus-supraspinatus tendon complex specimens were retrieved at 4,8,and 12 weeks after operation.The Mg alloy suture groups showed better biomechanical properties in terms of ultimate load to failure.Gross observation showed that hyperplastic response of the scar tissue at the tendon-bone interface is progressively alleviated over time in the both Mg alloy suture and Vicryl suture groups.In the histological analysis,for Mg alloy suture groups,chondrocytes appear to proliferate at 4 weeks postoperatively,and the tendon-bone interface showed an orderly structural transition zone at 8 weeks postoperatively.The collagenous fiber tended to be aligned and the tendon-bone interlocking structures apparently formed,where transitional structure from unmineralized fibrocartilage to mineralized fibrocartilage was closer to the native fibrocartilaginous enthesis.In vivo degradation of the magnesium alloy wire was completed within 12 weeks.The results indicated that Mg alloy wire was promising as degradable suture with the potential to promotes fibrocartilaginous interface regeneration in rotator cuff repair.
基金supported by the National Key Research and Development Program of China(No.2022YFB3707405)the Guangdong Basic and Applied Basic Research Foundation,China(No.2021A1515110525)+1 种基金the National Natural Science Foundation of China(Nos.U22A20114 and 52301200)the Liaoning Revitalization Talents Program,China(No.XLYC2007009)。
文摘A high-zinc composite,12vol%SiC/Al-13.3 Zn-3.27 Mg-1.07Cu(wt%),with an ultra-high-strength of 781 MPa was success-fully fabricated through a powder metallurgy method,followed by an extrusion process.The effects of solid-solution and aging heat treat-ments on the microstructure and mechanical properties of the composite were extensively investigated.Compared with a single-stage sol-id-solution treatment,a two-stage solid-solution treatment(470℃/1 h+480℃/1 h)exhibited a more effective solid-solution strengthen-ing owing to the higher degree of solid-solution and a more uniform microstructure.According to the aging hardness curves of the com-posite,the optimized aging parameter(100℃/22 h)was determined.Reducing the aging temperature and time resulted in finer and more uniform nanoscale precipitates but only yielded a marginal increase in tensile strength.The fractography analysis revealed that intergranu-lar cracking and interface debonding were the main fracture mechanisms in the ultra-high-strength SiC/Al-Zn-Mg-Cu composites.Weak regions,such as the SiC/Al interface containing numerous compounds and the precipitate-free zones at the high-angle grain boundaries,were identified as significant factors limiting the strength enhancement of the composite.Interfacial compounds,including MgO,MgZn2,and Cu5Zn8,reduced the interfacial bonding strength,leading to interfacial debonding.
基金supported by the National Natural Science Foundation of China(Nos.52271107 and 52205392)the Natural Science Foundation of Shandong Province(No.ZR2021ME241)the Bintech-IMR R&D Program(No.GYY-JSBU-2022-012).
文摘The basal texture of traditional magnesium alloy AZ31 is easy to form and exhibits poor plasticity at room temperature.To address these problems,a multi-micro-alloyed high-plasticity Mg-1.8Zn-0.8Gd-0.1Ca-0.2Mn(wt%)alloy was developed using the unique role of rare earth and Ca solute atoms.In addition,the influence of the annealing process on the grain size,second phase,texture,and mechanical properties of the warm-rolled sheet at room temperature was analyzed with the goal of developing high-plasticity mag-nesium alloy sheets and obtaining optimal thermal-mechanical treatment parameters.The results show that the annealing temperature has a significant effect on the microstructure and properties due to the low alloying content:there are small amounts of larger-sized block and long string phases along the rolling direction(RD),as well as several spherical and rodlike particle phases inside the grains.With increas-ing annealing temperature,the grain size decreases and then increases,and the morphology,number,and size of the second phase also change correspondingly.The particle phase within the grains vanishes at 450℃,and the grain size increases sharply.In the full recrystal-lization stage at 300-350℃,the optimum strength-plasticity comprehensive mechanical properties are presented,with yield strengths of 182.1 and 176.9 MPa,tensile strengths of 271.1 and 275.8 MPa in the RD and transverse direction(TD),and elongation values of 27.4%and 32.3%,respectively.Moreover,there are still some larger-sized phases in the alloy that influence its mechanical properties,which offers room for improvement.
基金the National Natural Science Foundation of China(Nos.52001310 and 52130002)the National Science and Technology Major Project(No.J2019-VI-0019-0134)+1 种基金KC Wong Education Foundation(No.GJTD-2020-09)Institute of Metal Res earch Innovation Fund(No.2023-ZD01)。
文摘Compared with the conventional Charpy impact test method,the oscillographic impact test can help in the behavioral analysis of materials during the fracture process.In this study,the trade-off relationship between the strength and toughness of a DZ2 axle steel at various tempering temperatures and the cause of the improvement in impact toughness was evaluated.The tempering process dramatically influenced carbide precipitation behavior,which resulted in different aspect ratios of carbides.Impact toughness improved along with the rise in tempering temperature mainly due to the increase in energy required in impact crack propagation.The characteristics of the impact crack propagation process were studied through a comprehensive analysis of stress distribution,oscilloscopic impact statistics,fracture morphology,and carbide morphology.The poor impact toughness of low-tempering-temperature specimens was attributed to the increased number of stress concentration points caused by carbide morphology in the small plastic zone during the propagation process,which resulted in a mixed distribution of brittle and ductile fractures on the fracture surface.
基金support from the China Manned Space Engineering(YYMT1201-EXP08).
文摘The tungsten fibers or powders reinforced Zr_(52)Cu_(32)Ni_(6)Al_(10),(Zr_(52)Cu_(32)Ni_(6)Al_(10))_(98)Nb_(2),and(Zr_(52)Cu_(32)Ni_(6)Al_(10))_(98)Be_(2)bulk metallic glass composites(BMGCs)were fabricated using the infiltration casting method.In this study,the wettability between the amorphous alloy melts and tungsten substrates was investigated using the sessile drop method,revealing excellent wettability at 1,010℃.Consequently,an infiltration temperature of 1,010°C was chosen for composite material fabrication.Structural characterization and mechanical property test of both composites were conducted through scanning electron microscopy(SEM),and X-ray diffraction(XRD),and universal mechanical testing.Both tungsten fiber or tungsten powder reinforced Zr_(52)Cu_(32)Ni_(6)Al_(10)and(Zr_(52)Cu_(32)Ni_(6)Al_(10))_(98)Be_(2)composites exhibit the formation of W-Zr phase.In contrast,the tungsten fiber or tungsten powder reinforced(Zr_(52)Cu_(32)Ni_(6)Al_(10))_(98)Nb_(2)composites does not show the formation of W-Zr phase.X-ray diffraction patterns confirm the presence of W reinforcement phases in both composites.The successful fabrication of both composites is evidenced by their remarkable mechanical properties under room temperature compression.The yield strength of all the three tungsten fiber-reinforced composite sample exceeds 2,400 MPa,with the plastic strain exceeding 3.9%,while the yield strength of all the three tungsten powder-reinforced composite sample surpasses 2,700 MPa,with the plastic strain exceeding 30%.Fracture analysis reveals longitudinal splitting in the tungsten fiber-reinforced composites,contrasting with brittle fracture in the tungsten powder-reinforced composites.The denser the shear bands on the amorphous matrix of the two types of composite materials,the better their mechanical properties.
基金financially supported by the Natural Science Foundation of Liaoning Province(No.2020-MS-004)the Natural Science Foundation of Liaoning(ZR2021ME241)+1 种基金the National Natural Science Foundation of China(Nos.51601193 and 51701218)the National Key Research and Development Program of China(No.2016YFB0301104)。
文摘The low-cycle fatigue behavior of solutionized(T4)and aged(T6)WE43 magnesium alloys was studied at room temperature.The total strain amplitudes(△ε_(t)/2)were 0.4%,0.5%,0.6%,0.7%and 1.0%.Detailed microstructure evolution was characterized by scanning electron microscope(SEM),electron backscattered diffraction(EBSD)and transmission electron microscopy(TEM).The results showed that plastic strain amplitude decreased with the increasing cycle number in T4 alloy,which is due to the dense persistent slip bands(PSBs)and dynamic precipitates hinderingdislocation slip.In contrast,the plastic strain amplitude increases gradually in T6 alloy,which is attributed to the enhanced activation of pyramidal slip.The low-cycle fatigue life of T6 alloy with larger fatigue ductility coefficient is longer than that of T4 alloy.The Coffin-Manson model can accurately predict the fatigue life of T4 and T6 alloys compared to Jahed-Varvani(JV)energy model.For T4 alloy,the fatigue damage mechanism was dominated by basal slip.For T6 alloy,the enhanced pyramidal slip plays an important role to accommodate plastic deformation.
基金the support of the China Manned Space Engineering(YYMT1201-EXP08)。
文摘The infiltration casting method is widely employed for the preparation of ex-situ composite materials.However,the production of composite materials using this method must necessitates a comprehensive understanding of the wettability and interface characteristics between the reinforcing phase and the bulk metallic glasses(BMGs).This work optimized the composition of Zr-based BMGs through microalloying methods,resulting in a new set of Zr-based BMGs with excellent glass-forming ability.Wetting experiments between the Zr-based BMGs melts and W substrates were conducted using the traditional sessile drop method,and the interfaces were characterized utilizing a scanning electron microscope(SEM)equipped with energy dispersive X-ray spectroscopy(EDS).The work demonstrates that the microalloying method substantially enhances the wettability of the Zr-based BMGs melt.Additionally,the incorporation of Nb element impedes the formation of W-Zr phases,but the introduction of Nb element does not alter the extent of interdiffusion between the constituent elements of the amorphous matrix and W element,indicating that the influence of Nb element on the diffusion of individual elements is minute.
基金the financial support by the Defense Industrial Technology Development Program(No.JCKY2020130C024)the National Science and Technology Major Project,China(No.Y2019-Ⅶ-0011-0151)the Science Center for Gas Turbine Project(No.P2022-C-Ⅳ-002-001)。
文摘Cracks have consistently been a significant challenge limiting the development of additive manufactured nickel-based superalloys.It is essential to investigate the location of cracks and their forming mechanism.This study extensively examines the impact of solidification process,microstructural evolution,and stress concentration on crack initiation during direct energy deposition(DED).The results emphasize that the crack formation is significantly related to large-angle grain boundaries,rapid cooling rates.Cracks caused by large-angle grain boundaries and a fast-cooling rate predominantly appear near the edge of the deposited samples.Liquation cracks are more likely to form near the top of the deposited sample,due to the presence ofγ/γ'eutectics.The secondary dendritic arm and the carbides in the interdendritic regions can obstruct liquid flow during the final stage of solidification,which results in the formation of solidification cracks and voids.This work paves the way to avoid cracks in nickel-based superalloys fabricated by DED,thereby enhancing the performance of superalloys.
基金National Science and Technology Major Project(2017-VI-0003-0073)Youth Innovation Promotion Association CAS under grant No.2021192+3 种基金National Natural Science Foundation of China(NSFC)under grant Nos.52130002 and 51901230IMR Innovation Fund(2023-ZD01)Liaoning"Unveiling and Commanding"Science and Technology plan(2022-37)KC Wong Education Foundation(GJTD-2020-09).
文摘The authors regret to inform that the whole“Acknowledgements”section is missing due to the composing process of the editing.The“Acknowledgements”information that should be added is as follows.
基金supported by the Shenyang Science and Technology Program(grant number 22-301-1-10).
文摘The design of the loading path is one of the important research contents of the tube hydroforming process.Optimization of loading paths using optimization algorithms has received attention due to the inefficiency of only finite element optimization.In this paper,the hydroforming process of 5A02 aluminum alloy variable diameter tube was as the research object.Fuzzy control was used to optimize the loading path,and the fuzzy rule base was established based on FEM.The minimum wall thickness and wall thickness reduction rate were determined as input membership functions,and the axial feeds variable value of the next step was used as output membership functions.The results show that the optimized loading path greatly improves the uniformity of wall thickness and the forming effect compared with the linear loading path.The round corner lamination rate of the tube is 91.2%under the fuzzy control optimized loading path,which was increased by 47.1%and 22.6%compared with linear loading Path 1 and Path 2,respectively.Based on the optimized loading path in the experiment,the minimum wall thickness of the variable diameter tube was 1.32 mm and the maximum thinning rate was 12.4%.The experimental results were consistent with the simulation results,which verified the accuracy of fuzzy control.The research results provide a reference for improving the forming quality of thin-walled tubes and plates.
基金financial supports from the Natural Science Foundation of Shandong Province(ZR2021ME241)the Natural Science Foundation of Liaoning Province(No.2020-MS-004)+2 种基金the National Natural Science Foundation of China(NSFC,Nos.51601193 and 51701218)State Key Program of National Natural Science of China(No.51531002)National Key Research and Development Program of China(No.2016YFB0301104).
文摘3%Y_(2)O_(3)p/ZGK200 composites were subjected to unidirectional rolling(UR)and cross rolling(CR)at 400℃and 350℃followed by annealing at 300℃for 1 h.The microstructure,texture and mechanical properties of rolled and annealed composites were systematically studied.The rolled composites exhibited a heterogeneous microstructure,consisting of deformed grains elongated along rolling direction(RD)and Y_(2)O_(3)particles bands distributed along RD.After annealing,static recrystallization(SRX)occurred and most deformed grains transformed into equiaxed grains.A non-basal texture with two strong T-texture components was obtained after UR while a non-basal elliptical/circle texture with circle multi-peaks was obtained after CR,indicating that rolling path had great influences on texture of the composites.After annealing process,R-texture component disappeared or weakened,as results,a non-basal texture with double peaks tilting from normal direction(ND)to transverse direction(TD)and a more random non-basal texture with circle multi-peaks were obtained for UR and CR composites,respectively.The yield strength of rolled composites after UR showed obvious anisotropy along RD and TD while a low anisotropic yield strength was obtained after CR.Some Y_(2)O_(3)particles broke during rolling.The fracture of the composites was attributed to the existence of Y_(2)O_(3)clusters and interfacial debonding between particles and matrix during tension,as a result,the ductility was not as superior as matrix alloy.
基金financially supported by the National Key R&D Program of China under grant No.2017YFB0703002the National Natural Science Foundation of China(NSFC)under grant Nos.U1664253,51901230,51871223,51790482,51771208+3 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences under grant No.XDB22020202the Youth Innovation Promotion Association CAS under grant No.2018226the National Science and Technology Major Project under grant No.2017-VI-0003-0073the LiaoNing Revitalization Talents Program under Grant No.XLYC1808027。
文摘The high cost and low efficiency of fatigue tests are bottleneck problem for the anti-fatigue design of metallic materials.For this problem,a theoretical fatigue model is proposed in this study,the possible applications have also been discussed.Specific results would be introduced in two serial papers,in which the first paper focuses on the model building and the applications on fatigue strength prediction;the second paper put emphasis on the influencing factors of the model parameters and the applications on fatigue strength improvement.In this first paper,a theoretical model is proposed considering both the strength and plastic restrictions of fatigue strength.As the model builds up a brief relationship among yield strength(Y),tensile strength(T)and fatigue strength(F),it is named as the Y-T-F model.Through the verification with fatigue strength data covering various kinds of metallic materials and loading conditions,this Y-T-F model exhibits both generality and accuracy.With the Y-T-F model,the efficient fatigue strength prediction could be conducted by brief linear fitting and calculation,just through yield strength,tensile strength and several known fatigue strength data.Moreover,through its deduced Y-F model,the analytical formula of fatigue strength continuously changing with materials strengthening can be obtained,as well as the maximum value of fatigue strength and corresponding critical yield strength.In summary,the Y-T-F model would be useful for reducing the fatigue tests,thus providing new possibilities on the efficient anti-fatigue design and selection of metallic materials.
基金financially supported by the National Key R&D Program of China under grant No.2017YFB0703002the National Natural Science Foundation of China(NSFC)under grant Nos.U1664253,51901230,51871223,51790482,51501198,51771208,51331007+3 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences under grant No.XDB22020202the Youth Innovation Promotion Association CAS under grant No.2018226the National Science and Technology Major Project under grant No.2017-VI-0003-0073the LiaoNing Revitalization Talents Program under Grant No.XLYC1808027。
文摘In the first paper,a Y-T-F model was proposed based on the restrictions of both strength and plasticity;the corresponding applications on the fatigue strength prediction have also been discussed.In this second paper,the emphasis will be put on the issues of fatigue strength improvement.Based on the primary form of the Y-T-F model,the parameters are further analyzed and quantified,to clarify the influences of various factors on fatigue strength.Firstly,the damage capacity C is proved to be sensitive to the elastic modulus E,which could change with the alloying components and nano-scaled grain boundaries;the increase of E would lead to the increasing C,thus increase the fatigue strength.Secondly,the microstructure characteristic coefficient a,as well as the yield strengthσ_(y) and tensile strengthσ_(b) in the crack initiation region could be influenced by the processing mode,grain size and microstructure uniformity of materials;the change of microstructure characteristics would affect the changing tendency of tensile strength--fatigue strength relation via varying the values of a,σ_(y) andσ_(b).Thirdly,the damage weight coefficientωis found to be a reflection of the fatigue strength declination induced by defects;the defect dimension D,the defect shape correlated stress concentration coefficient Kt,as well as the strengthening level of matrix materialsσ_(b) are all corresponding factors.Quantified correlations between the above parameters and corresponding factors are comprehensively built up,hence obtaining the influences of either a single factor or multiple factors on fatigue strength.This further developed Y-T-F model would be helpful to clarify the direction of fatigue strength improvement,and contribute to the anti-fatigue design optimization of metallic materials.
基金Projects(51901231,51971227,51771210,51774264)supported by the National Natural Science Foundation of ChinaProject(2019-BS-253)supported by the Natural Science Foundation of Liaoning Province,China。
文摘Solidification experiments were carried out to investigate the kinetic behaviour of TiB2 particles in Al melt and their effect on the grain refinement of commercially-pure Al.A model was proposed to describe the kinetic behaviour of TiB2 particles during the whole process from the addition of TiB2 to the melt to the freezing of the melt.The results indicate that TiB2 particles are not stable in Al melt.They may dissolve and coarsen during the holding period and grow during the cooling period of the melt.The kinetic behaviour of TiB2 particles in the melt has a great influence on their number density and the grain refinement.Solute Ti addition can suppress the dissolution,Ostwald ripening and growth behaviours of TiB2 particles.
