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
The modification and refinement of Mg2Si phase is thought to be one of the key aspects to improve the mechanical properties of Si-containing magnesium alloys. In this article, the effects of Sr on the microstructure, ...The modification and refinement of Mg2Si phase is thought to be one of the key aspects to improve the mechanical properties of Si-containing magnesium alloys. In this article, the effects of Sr on the microstructure, tensile and creep properties of AZ61-0.7Si magnesium alloy were investigated. The results indicate that adding small amounts of Sr to AZ61-0.7Si alloy can modify and refine Chinese script shaped Mg2Si phases in the alloy. After adding 0.03wt%-0.09wt% Sr to AZ61-0.7Si alloy, the Mg2Si phases in the alloy change from the coarse Chinese script shape to fine granule and/or irregular polygonal shapes. The modification and refinement mechanisms of Mg2Si phases in Sr-containing AZ61-0.7Si alloys are possibly related to the reduction of growth rate and the enhancement of nucleation ratio for Mg2Si particles during the solidification process. Owing to the modification and refinement of Mg2Si phases, the tensile and creep properties of Sr-containing AZ61-0.7Si alloys are greatly improved.展开更多
Magnesium alloy has been considered as one of the third-generation biomaterials for the regeneration and support of functional bone tissue.As a regeneration implant material with great potential applications,in-situ M...Magnesium alloy has been considered as one of the third-generation biomaterials for the regeneration and support of functional bone tissue.As a regeneration implant material with great potential applications,in-situ Mg_(2)Si phase reinforced Mg-6Zn cast alloy was comprehensively studied and expected to possess excellent mechanical properties via the refining and modifying of Mg_(2)Si reinforcements.The present study demonstrates that the primary and eutectic Mg_(2)Si phase can be greatly modified by the yttrium(Y)addition.The size of the primary Mg_(2)Si phases can be reduced to~20μm with an addition of 0.5 wt.%Y.This phenomenon is mainly attributed to the poisoning effect of the Y element.Moreover,wear resistance and tensile properties of the ternary alloy have also been improved by the Y addition.Mg-6Zn-4Si-0.5Y alloy exhibits optimal tensile properties and wears resistance.The ultimate tensile strength and the elongation of the alloy with 0.5 wt.%Y are 50%and 65%higher than those of the ternary alloy,respectively.Excessive Y addition(1.0 wt.%)deteriorates the tensile properties of Mg-Zn-Si alloy.The improvement of the tensile properties is mainly due to the modification of primary and eutectic Mg_(2)Si phases as well as the solid solution strengthening of the Y atoms.This study provides a certain implication for the application of Mg-Zn-Si alloys containing Y elements as regeneration implants.展开更多
The microstructure, microhardness and tensile properties of laser additive manufactured (LAM) Ti?5Al?2Sn?2Zr?4Mo?4Cr alloy were investigated. The result shows that the microstructure evolution is strongly affected by ...The microstructure, microhardness and tensile properties of laser additive manufactured (LAM) Ti?5Al?2Sn?2Zr?4Mo?4Cr alloy were investigated. The result shows that the microstructure evolution is strongly affected by the thermal history of LAM process. Primary α (αp) with different morphologies, secondary α (αs) and martensite α' can be observed at different positions of the LAMed specimen. Annealing treatment can promote the precipitation of rib-like α phase or acicular α phase. As a result, it can increase or decrease the microhardness. The as-deposited L-direction and T-direction specimens contain the same phase constituent with different morphologies. The tensile properties of the as-deposited LAMed specimens are characterized of anisotropy. The L-direction specimen shows the character of low strength but high ductility when compared with the T-direction specimen. After annealing treatment, the strength of L-direction specimen increases significantly while the ductility reduces. The strength of the annealed T-direction specimen changes little, however, the ductility reduces nearly by 50%.展开更多
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supported by the National Science Fund for Distinguished Young Scholars (No.50725413)the Major State Basic Research and Development Program of China (No.2007CB613704)+1 种基金the Natural Science Foundation Project of CQ CSTC (No.2007BB4400)Chongqing Science and Technology Commission in China (No.2006AA4012-9-6)
文摘The modification and refinement of Mg2Si phase is thought to be one of the key aspects to improve the mechanical properties of Si-containing magnesium alloys. In this article, the effects of Sr on the microstructure, tensile and creep properties of AZ61-0.7Si magnesium alloy were investigated. The results indicate that adding small amounts of Sr to AZ61-0.7Si alloy can modify and refine Chinese script shaped Mg2Si phases in the alloy. After adding 0.03wt%-0.09wt% Sr to AZ61-0.7Si alloy, the Mg2Si phases in the alloy change from the coarse Chinese script shape to fine granule and/or irregular polygonal shapes. The modification and refinement mechanisms of Mg2Si phases in Sr-containing AZ61-0.7Si alloys are possibly related to the reduction of growth rate and the enhancement of nucleation ratio for Mg2Si particles during the solidification process. Owing to the modification and refinement of Mg2Si phases, the tensile and creep properties of Sr-containing AZ61-0.7Si alloys are greatly improved.
基金supported by Natural Science Foundation of the Jiangsu Higher Education Institutions of China(19KJD430004)the Fund of the Jiangsu CHINA-ISRAEL Industrial Technology Research Institute and Changzhou Sci&Tech Program(Nos.CJ20190042,CJ20200046).
文摘Magnesium alloy has been considered as one of the third-generation biomaterials for the regeneration and support of functional bone tissue.As a regeneration implant material with great potential applications,in-situ Mg_(2)Si phase reinforced Mg-6Zn cast alloy was comprehensively studied and expected to possess excellent mechanical properties via the refining and modifying of Mg_(2)Si reinforcements.The present study demonstrates that the primary and eutectic Mg_(2)Si phase can be greatly modified by the yttrium(Y)addition.The size of the primary Mg_(2)Si phases can be reduced to~20μm with an addition of 0.5 wt.%Y.This phenomenon is mainly attributed to the poisoning effect of the Y element.Moreover,wear resistance and tensile properties of the ternary alloy have also been improved by the Y addition.Mg-6Zn-4Si-0.5Y alloy exhibits optimal tensile properties and wears resistance.The ultimate tensile strength and the elongation of the alloy with 0.5 wt.%Y are 50%and 65%higher than those of the ternary alloy,respectively.Excessive Y addition(1.0 wt.%)deteriorates the tensile properties of Mg-Zn-Si alloy.The improvement of the tensile properties is mainly due to the modification of primary and eutectic Mg_(2)Si phases as well as the solid solution strengthening of the Y atoms.This study provides a certain implication for the application of Mg-Zn-Si alloys containing Y elements as regeneration implants.
基金Projects(51105311,51475380)supported by the National Natural Science Foundation of ChinaProject(2013AA031103)supported by the National High-Tech Research and Development Program of China
文摘The microstructure, microhardness and tensile properties of laser additive manufactured (LAM) Ti?5Al?2Sn?2Zr?4Mo?4Cr alloy were investigated. The result shows that the microstructure evolution is strongly affected by the thermal history of LAM process. Primary α (αp) with different morphologies, secondary α (αs) and martensite α' can be observed at different positions of the LAMed specimen. Annealing treatment can promote the precipitation of rib-like α phase or acicular α phase. As a result, it can increase or decrease the microhardness. The as-deposited L-direction and T-direction specimens contain the same phase constituent with different morphologies. The tensile properties of the as-deposited LAMed specimens are characterized of anisotropy. The L-direction specimen shows the character of low strength but high ductility when compared with the T-direction specimen. After annealing treatment, the strength of L-direction specimen increases significantly while the ductility reduces. The strength of the annealed T-direction specimen changes little, however, the ductility reduces nearly by 50%.
