The mechanical alloying of FeNiPB(Cu, Nb) mixed powders was studied by X-ray diffraction (XRD), transition electron microscope (TEM), scanning electron microscopy (SEM) and extended X-ray absorption fine structure (EX...The mechanical alloying of FeNiPB(Cu, Nb) mixed powders was studied by X-ray diffraction (XRD), transition electron microscope (TEM), scanning electron microscopy (SEM) and extended X-ray absorption fine structure (EXAFS). The results show that the FeNiPB(Cu, Nb) mixed powders alloy after milling for 20 h, as the milling time increases to 80h, Fe and Ni atoms are in an amorphous environment, the morphology of FeNiPB(Cu, Nb) mixed powders appears as cotton fiber and its electron diffraction pattern shows a typically diffuse amorphous halo. So FeNiPB(Cu, Nb) mixed powders transform to amorphous state under this condition. After the FeNiPB(Cu, Nb) amorphous alloy was heated at 520℃ for 1 h, the nanocrystalline FeNiPB(Cu, Nb) was produced. So, the Fe-based nanocrystalline alloy can be prepared by partially crystallizing the FeNiPB(Cu, Nb) amorphous alloy.展开更多
Cu−2Cr−1Nb alloy was fabricated by spark plasma sintering(SPS)using close coupled argon-atomized alloy powder as the raw material.The optimal SPS parameters obtained using the L9(3^(4))orthogonal test were 950℃,50 MP...Cu−2Cr−1Nb alloy was fabricated by spark plasma sintering(SPS)using close coupled argon-atomized alloy powder as the raw material.The optimal SPS parameters obtained using the L9(3^(4))orthogonal test were 950℃,50 MPa and 15 min,and the relative density of the as-sintered alloy was 99.8%.The rapid densification of SPS effectively inhibited the growth of the Cr_(2)Nb phase,and the atomized powder microstructure was maintained in the grains of the alloy matrix.Uniformly distributed multi-scale Cr_(2)Nb phases with grain sizes of 0.10−0.40μm and 20−100 nm and fine grains of alloy matrix with an average size of 3.79μm were obtained.After heat treatment at 500℃ for 2 h,the room temperature tensile strength,electrical conductivity,and thermal conductivity of the sintered Cu−2Cr−1Nb alloy were 332 MPa,86.7%(IACS),and 323.1 W/(m·K),respectively,and the high temperature tensile strength(700℃)was 76 MPa.展开更多
A novel Cu−4.8Cr−2.2Nb−0.15Y(at.%)alloy was fabricated by employing the laser powder bed fusion with different processing parameters.The influence of laser power(P),scanning speed(v),and laser linear energy density(El...A novel Cu−4.8Cr−2.2Nb−0.15Y(at.%)alloy was fabricated by employing the laser powder bed fusion with different processing parameters.The influence of laser power(P),scanning speed(v),and laser linear energy density(El)on the defects,melt pool morphology,microstructure,and properties of the alloy was systematically investigated.The results show that the optimized process parameters for preparing Cu−Cr−Nb−Y alloy with relative density over 99.5%are P=300−350 W and v=650−800 mm/s,corresponding to El=0.375−0.538 J/mm.When E_(l)<0.3 J/mm,increasing P or decreasing v can enhance the continuity and size of the melt pool,reduce the lack-of-fusion defects,and increase the relative density.However,excessively high E_(l)leads to a deeper melt pool,more keyholes,and reduced relative density.The grain size of the as-built Cu−Cr−Nb−Y alloy shows a bimodal distribution,with fine grains at the center and coarse grains at the edge of the melt pool.Increasing P or decreasing v increases the average grain size and〈110〉texture intensity.The alloy fabricated with P=350 W and v=800 mm/s displays the highest relative density of 99.82%.The yield strength,tensile strength,and elongation are(443±5)MPa,(699±4)MPa,and(17.1±0.7)%,respectively.展开更多
文摘The mechanical alloying of FeNiPB(Cu, Nb) mixed powders was studied by X-ray diffraction (XRD), transition electron microscope (TEM), scanning electron microscopy (SEM) and extended X-ray absorption fine structure (EXAFS). The results show that the FeNiPB(Cu, Nb) mixed powders alloy after milling for 20 h, as the milling time increases to 80h, Fe and Ni atoms are in an amorphous environment, the morphology of FeNiPB(Cu, Nb) mixed powders appears as cotton fiber and its electron diffraction pattern shows a typically diffuse amorphous halo. So FeNiPB(Cu, Nb) mixed powders transform to amorphous state under this condition. After the FeNiPB(Cu, Nb) amorphous alloy was heated at 520℃ for 1 h, the nanocrystalline FeNiPB(Cu, Nb) was produced. So, the Fe-based nanocrystalline alloy can be prepared by partially crystallizing the FeNiPB(Cu, Nb) amorphous alloy.
基金financially supported by the National Key Research and Development Program of China (No.2016YFB0301300)Innovation Driven Project of Central South University,China (No.2015CX004)+1 种基金State Key Laboratory of Powder Metallurgy,Central South University,Chinathe Open Fund of National Joint Engineering Research Center for Abrasion Control and Molding of Metal Materials,China (No.HKDNM201907)。
文摘Cu−2Cr−1Nb alloy was fabricated by spark plasma sintering(SPS)using close coupled argon-atomized alloy powder as the raw material.The optimal SPS parameters obtained using the L9(3^(4))orthogonal test were 950℃,50 MPa and 15 min,and the relative density of the as-sintered alloy was 99.8%.The rapid densification of SPS effectively inhibited the growth of the Cr_(2)Nb phase,and the atomized powder microstructure was maintained in the grains of the alloy matrix.Uniformly distributed multi-scale Cr_(2)Nb phases with grain sizes of 0.10−0.40μm and 20−100 nm and fine grains of alloy matrix with an average size of 3.79μm were obtained.After heat treatment at 500℃ for 2 h,the room temperature tensile strength,electrical conductivity,and thermal conductivity of the sintered Cu−2Cr−1Nb alloy were 332 MPa,86.7%(IACS),and 323.1 W/(m·K),respectively,and the high temperature tensile strength(700℃)was 76 MPa.
基金financially supported by the Project of Chinese Academy of Engineering(Nos.2019-XZ-11 and 2023-XY-18)the Open Fund of National Joint Engineering Research Center for Abrasion Control and Molding of Metal Materials of China(No.HKDNM201907)。
文摘A novel Cu−4.8Cr−2.2Nb−0.15Y(at.%)alloy was fabricated by employing the laser powder bed fusion with different processing parameters.The influence of laser power(P),scanning speed(v),and laser linear energy density(El)on the defects,melt pool morphology,microstructure,and properties of the alloy was systematically investigated.The results show that the optimized process parameters for preparing Cu−Cr−Nb−Y alloy with relative density over 99.5%are P=300−350 W and v=650−800 mm/s,corresponding to El=0.375−0.538 J/mm.When E_(l)<0.3 J/mm,increasing P or decreasing v can enhance the continuity and size of the melt pool,reduce the lack-of-fusion defects,and increase the relative density.However,excessively high E_(l)leads to a deeper melt pool,more keyholes,and reduced relative density.The grain size of the as-built Cu−Cr−Nb−Y alloy shows a bimodal distribution,with fine grains at the center and coarse grains at the edge of the melt pool.Increasing P or decreasing v increases the average grain size and〈110〉texture intensity.The alloy fabricated with P=350 W and v=800 mm/s displays the highest relative density of 99.82%.The yield strength,tensile strength,and elongation are(443±5)MPa,(699±4)MPa,and(17.1±0.7)%,respectively.
