This study investigated the influence of the addition of Al to a Mg-7Bi(B7,wt%)alloy,particularly its recrystallization behavior during extrusion and its resulting mechanical properties.The addition of 2 wt%Al to the ...This study investigated the influence of the addition of Al to a Mg-7Bi(B7,wt%)alloy,particularly its recrystallization behavior during extrusion and its resulting mechanical properties.The addition of 2 wt%Al to the B7 alloy resulted in a lower grain size,a reduction in the number density of fine Mg3Bi2 particles,and a higher area fraction of relatively coarse Mg3Bi2 particles in the extrusion billet.These microstructural changes increased the nucleation sites for recrystallization,reduced the Zener pinning effect,and enhanced particle-stimulated nucleation,all of which promoted dynamic recrystallization behavior during extrusion.As a result,the area fraction of recrystallized grains in the extruded alloy increased from 77%to 94%.The extruded B7 alloy exhibited a strong<10-10>fiber texture,whereas the extruded Mg-7Bi-2Al(BA72)alloy had a weak<10-10>-<2-1-10>texture,which was attributed to the minimal presence of unrecrystallized grains and the dispersed orientation of the recrystallized grains.The tensile yield strength(TYS)of the extruded BA72 alloy was higher than that of the extruded B7 alloy(170 and 124 MPa,respectively),which resulted from the enhanced grain-boundary and solid-solution strengthening effects.The tensile elongation(EL)of the BA72 alloy also exceeded that of the B7 alloy(20.3%and 6.1%,respectively),the result of the uniform formation of fine twins under tension in the former and the formation of a few coarse twins among the unrecrystallized grains in the latter.Consequently,the addition of a small amount of Al to the B7 alloy significantly improved both the strength and ductility of the extruded alloy,resulting in a remarkable increase in the product of the TYS and EL from 756 to 3451 MPa%and expanding its potential range of applications as a lightweight extruded structural component.展开更多
This study investigates the effect of the deformation mode on the precipitation behavior of an extruded Mg-8.0Al-0.5Zn-0.2Mn(AZ80)alloy.The alloy samples are compared after the application of 3.5%tension and 3.5%compr...This study investigates the effect of the deformation mode on the precipitation behavior of an extruded Mg-8.0Al-0.5Zn-0.2Mn(AZ80)alloy.The alloy samples are compared after the application of 3.5%tension and 3.5%compression along the extrusion direction to induce slip-dominant and twinning-dominant deformation modes,respectively.The pre-compressed(PC)sample,which contained numerous{10-12}tension twins,has a reduced grain size and a higher internal strain than the pre-tensioned(PT)sample,which is attributed to the inherent internal strain that occurs during the formation and growth of the twins.As a result,the precipitation behavior of the PC sample is accelerated,leading to its short peak aging time of 32 h,which is lower than those of the PT and as-extruded samples(48 and 100 h,respectively).Furthermore,fine continuous precipitates(CPs)rapidly form within the{10-12}twins,contributing to the enhanced hardness.Discontinuous precipitates(DPs),which have a hardness comparable to the CP-containing twinned regions,in the PC sample experience less coarsening during aging than those in the PT sample due to growth inhibition by the{10-12}twins.Ultimately,the{10-12}twins generated under the twinning-dominant deformation condition lead to enhanced precipitation behaviors,including the preferential formation and refinement of CPs and the suppressed coarsening of DPs.Consequently,pre-deformation that occurs{10-12}twinning exhibits more pronounced effects on precipitation acceleration and microstructural modification than slip-inducing pre-deformation.展开更多
The suspensions of the powder mixture of yttria and alumina were prepared by the aqueous tape casting method. Rodia DP270, Dolapix CE64, citric acid and Dammonium 3008 were used as dispersing agents. The morphologies ...The suspensions of the powder mixture of yttria and alumina were prepared by the aqueous tape casting method. Rodia DP270, Dolapix CE64, citric acid and Dammonium 3008 were used as dispersing agents. The morphologies of the powders and the fracture surface of the green body were observed by scanning electron microscopy （SEM）. The zeta potential test was employed to characterize the surface charge states of different suspensions. The dispersion of the suspensions was analyzed by the rheological tests and the sedimentation experiments. The results indicated that the yttria and alumina powder mixtures were well dispersed by the dis- persing agents. The rheological curves showed shear thinning behavior. The most efficient dispersing agent was Dammonium 3008. The optimum usage of Dammonium 3008 was 1.0 wt.%. The green body was dense and no interface between the adjacent layers was found. The in-line transmittance of the as-sintered YAG ceramic was higher than 80% between 400 and 1100 urn.展开更多
This study describes the development of a one-pot strategy to produce spherical alloy microparticles for advanced near-net-shape manufacturing processes, including additive manufacturing and powder injection molding. ...This study describes the development of a one-pot strategy to produce spherical alloy microparticles for advanced near-net-shape manufacturing processes, including additive manufacturing and powder injection molding. The Al Si12 eutectic alloy(ca. 12 wt% Si) system was chosen as the model with which the main experiments were carried out. The proposed process synergistically integrates a few common,low-cost processing techniques including the mixing of Al micrometer size particles with silicon and sodium chloride, heat-treating the mixture at temperatures of 650–810°C, and the dissolution of salt in water to produce spherical Al Si12 alloy particles without the need to rely on costly melting and atomizing techniques. This new process can use laow-cost source Al and Si powders as the raw materials to produce10–200 um-sized spherical particles of Al Si12. The Ansys-CFX computational fluid dynamics software was used to analyze the flow behavior of Al Si12 liquid droplets and particle size refinement in the narrow voids of the sample.展开更多
基金supported by the Materials and Components Technology Development Program(No.20024843)funded by the Ministry of Trade,Industry,and Energy(MOTIE,South Korea)+1 种基金the National Research Foundation of Korea(NRF)grant(No.RS-2023-00244478)funded by the Ministry of Science,ICT,and Future Planning(MSIP,South Korea).
文摘This study investigated the influence of the addition of Al to a Mg-7Bi(B7,wt%)alloy,particularly its recrystallization behavior during extrusion and its resulting mechanical properties.The addition of 2 wt%Al to the B7 alloy resulted in a lower grain size,a reduction in the number density of fine Mg3Bi2 particles,and a higher area fraction of relatively coarse Mg3Bi2 particles in the extrusion billet.These microstructural changes increased the nucleation sites for recrystallization,reduced the Zener pinning effect,and enhanced particle-stimulated nucleation,all of which promoted dynamic recrystallization behavior during extrusion.As a result,the area fraction of recrystallized grains in the extruded alloy increased from 77%to 94%.The extruded B7 alloy exhibited a strong<10-10>fiber texture,whereas the extruded Mg-7Bi-2Al(BA72)alloy had a weak<10-10>-<2-1-10>texture,which was attributed to the minimal presence of unrecrystallized grains and the dispersed orientation of the recrystallized grains.The tensile yield strength(TYS)of the extruded BA72 alloy was higher than that of the extruded B7 alloy(170 and 124 MPa,respectively),which resulted from the enhanced grain-boundary and solid-solution strengthening effects.The tensile elongation(EL)of the BA72 alloy also exceeded that of the B7 alloy(20.3%and 6.1%,respectively),the result of the uniform formation of fine twins under tension in the former and the formation of a few coarse twins among the unrecrystallized grains in the latter.Consequently,the addition of a small amount of Al to the B7 alloy significantly improved both the strength and ductility of the extruded alloy,resulting in a remarkable increase in the product of the TYS and EL from 756 to 3451 MPa%and expanding its potential range of applications as a lightweight extruded structural component.
基金supported by the National Research Foundation of Korea(NRF)grants funded by the Korea government(MSIT)(Nos.RS-2024-00351052 and RS-2024-00450561).
文摘This study investigates the effect of the deformation mode on the precipitation behavior of an extruded Mg-8.0Al-0.5Zn-0.2Mn(AZ80)alloy.The alloy samples are compared after the application of 3.5%tension and 3.5%compression along the extrusion direction to induce slip-dominant and twinning-dominant deformation modes,respectively.The pre-compressed(PC)sample,which contained numerous{10-12}tension twins,has a reduced grain size and a higher internal strain than the pre-tensioned(PT)sample,which is attributed to the inherent internal strain that occurs during the formation and growth of the twins.As a result,the precipitation behavior of the PC sample is accelerated,leading to its short peak aging time of 32 h,which is lower than those of the PT and as-extruded samples(48 and 100 h,respectively).Furthermore,fine continuous precipitates(CPs)rapidly form within the{10-12}twins,contributing to the enhanced hardness.Discontinuous precipitates(DPs),which have a hardness comparable to the CP-containing twinned regions,in the PC sample experience less coarsening during aging than those in the PT sample due to growth inhibition by the{10-12}twins.Ultimately,the{10-12}twins generated under the twinning-dominant deformation condition lead to enhanced precipitation behaviors,including the preferential formation and refinement of CPs and the suppressed coarsening of DPs.Consequently,pre-deformation that occurs{10-12}twinning exhibits more pronounced effects on precipitation acceleration and microstructural modification than slip-inducing pre-deformation.
基金supported by National Natural Science Foundation of China(51002172,90122035)the Development Program of China(2010AA03015887003)
文摘The suspensions of the powder mixture of yttria and alumina were prepared by the aqueous tape casting method. Rodia DP270, Dolapix CE64, citric acid and Dammonium 3008 were used as dispersing agents. The morphologies of the powders and the fracture surface of the green body were observed by scanning electron microscopy （SEM）. The zeta potential test was employed to characterize the surface charge states of different suspensions. The dispersion of the suspensions was analyzed by the rheological tests and the sedimentation experiments. The results indicated that the yttria and alumina powder mixtures were well dispersed by the dis- persing agents. The rheological curves showed shear thinning behavior. The most efficient dispersing agent was Dammonium 3008. The optimum usage of Dammonium 3008 was 1.0 wt.%. The green body was dense and no interface between the adjacent layers was found. The in-line transmittance of the as-sintered YAG ceramic was higher than 80% between 400 and 1100 urn.
基金supported by the Technology Innovation Program(10063427,development of eco-friendly smelting technology for the production of rare metal production for lowering manufacturing costs using solid oxide membrane)funded by the Ministry of Trade,Industry&Energy(MOTIE,Korea)the Competency Development Program for Industry Specialists of the Korean Ministry of Trade,Industry and Energy(MOTIE),operated by Korea Institute for Advancement of Technology(KIAT).(No.P0002019,HRD Program for High Value-Added Metallic Material Expert)supported by the Basic Research Laboratory Program through the Ministry of Education of the Republic of Korea(2019R1A4A1026125)。
文摘This study describes the development of a one-pot strategy to produce spherical alloy microparticles for advanced near-net-shape manufacturing processes, including additive manufacturing and powder injection molding. The Al Si12 eutectic alloy(ca. 12 wt% Si) system was chosen as the model with which the main experiments were carried out. The proposed process synergistically integrates a few common,low-cost processing techniques including the mixing of Al micrometer size particles with silicon and sodium chloride, heat-treating the mixture at temperatures of 650–810°C, and the dissolution of salt in water to produce spherical Al Si12 alloy particles without the need to rely on costly melting and atomizing techniques. This new process can use laow-cost source Al and Si powders as the raw materials to produce10–200 um-sized spherical particles of Al Si12. The Ansys-CFX computational fluid dynamics software was used to analyze the flow behavior of Al Si12 liquid droplets and particle size refinement in the narrow voids of the sample.
