Enhanced mechanical property by introducing bimodal grains structures in Cu-Ta alloys fabricated by mechanical alloying  

作　　者：Ningyu Li Yongqin Chang Mingyang Li Yuxiang Chen Xinrui Luo Shichao Pei Fan Yang 

机构地区：[1]School of Materials Science and Engineering,University of Science and Technology Beijing,Beijing 100083,China [2]Xi’an Rare Metal Materials Institute Co.Ltd,Xi’an 710016,China

出　　处：《Journal of Materials Science & Technology》2024年第5期104-112,共9页材料科学技术（英文版）

基　　金：supported by the National Natural Science Foundation of China(Nos.51971021,52203382,and U1967212);the National Magnetic Confinement Fusion Program of China(Nos.2019YFE03120004 and 2019YFE03130002);the Natu-ral Science Basic Research Plan in Shaanxi Province of China(No.2022JQ-439).

摘　　要：Dispersion-strengthened copper alloys can achieve ultra-high strength,but usually at the expense of duc-tility.In this study,a strategy for overcoming strength-ductility tradeoffof Cu alloys is realized through the introduction of bimodal grains structures.Cu-Ta alloys with only 0.5 at.%Ta content were successfully prepared by mechanical alloying combined with spark plasm sintering.The samples prepared by one-step and two-step ball milling methods are named as Cu-Ta(Ⅰ)and Cu-Ta(Ⅱ),respectively.The microstructural characterizations revealed that ultra-fine equiaxed grains with uniformly dispersed Ta precipitates were obtained in the Cu-Ta alloys.High strength of 377 MPa for yield strength together with elongation of∼8%was obtained in Cu-Ta(Ⅰ).Bimodal grains structures composed of fine-grain zones and coarse-grain zones were successfully introduced into Cu-Ta(Ⅱ)by a two-step ball milling approach,and both yield strength(463 MPa)and elongation(∼15%)were significantly synergistic enhanced.The hardness values of both Cu-Ta(Ⅰ)and Cu-Ta(Ⅱ)were almost kept nearly constant with the increase of annealing time,and the softening temperatures of Cu-Ta(Ⅰ)and Cu-Ta(Ⅱ)are 1018 and 1013℃,reaching 93.9%and 93.5%T m of pure Cu(1083℃),respectively.It reveals that the Cu-0.5 at.%Ta alloys exhibit excellent thermal stability and exceptional softening resistance.Ta nanoclusters with semi-coherent structures play an essential role in enhancing the strength and microstructural stability of alloys.Bimodal structures are beneficial to the activation of back stress strengthening and the initiation and propagation of microcracks,thus obtaining the extraordinary combination of strength and elongation.This study provides a new way to fabricate dispersion-strengthened Cu alloys with high strength,high elongation,excellent thermal stability and softening resistance,which have potential application value in the field of the future fusion reactor.

关 键 词：Cu-Ta alloy Mechanical alloying Ta precipitates Bimodal structures Mechanical property 

分 类 号：TG1[金属学及工艺—金属学]