含Cu高熵合金的组织结构和力学性能分析

高熵合金（HEAs）是一种由5种或5种以上元素以接近等原子比的方式混合而成的一种新型合金。HEAs的概念为开发具有独特性能的先进材料提供了新的途径，这是传统的基于单一主导元素的微合金化方法无法实现的。由于Cu元素与HEAs中其他元素的混合焓均为正值，因而更容易偏聚形成富Cu的面心立方（fcc）结构。本文主要总结了合金成分、制备方法对含Cu HEAs组织结构的影响规律以及含Cu HEAs的热稳定性。例如Al的添加会使CoCrCuFeNi合金从fcc单相转变为fcc+bcc的双相结构，而Ni含量的增加则会将AlCoCrCuNi的多相组织转变为单相fcc结构。与传统铸造工艺相比，选区激光熔化和喷溅急冷等具有极高的冷却速度，限制了元素的扩散，因而制备而成的AlCoCuFeNi和AlCoCrCuFeNi合金均是bcc结构。组织结构的改变会进一步影响含Cu HEAs力学性能，因而本文也探讨了合金成分、制备工艺和服役温度与力学性能的关系。例如，V的添加可以提高合金的强度，以先进制备方法如选区激光熔化或激光粉末熔融得到的合金具有优于铸造合金的力学性能。

Microstructure and Mechanical Property of Cu-Contained High-Entropy Alloys

High-entropy alloys (HEAs), consisting of five or more than five elements in near equimolar ratios, have attracted an increasing attention recently. The unique design concept introduces many unusual properties to HEAs, which cannot be achieved by traditional alloy design based on one dominate element. Due to the positive mixing enthalpies with other elements in HEAs, Cu element normally segregates and forms Cu-rich face-centered cubic (fcc) structure in Cu-contained HEAs. This paper briefly reviewed the effect of alloying element, preparation method on the microstructure evolution of Cu-contained HEAs as well as the thermal stability of Cu-contained HEAs. For example, the addition of Al would change the structure of CoCrCuFeNi alloy from fcc single phase to fcc+bcc dual phases. While in AlCoCrCuNi alloy, multi-phase would transfer to single phase with the increase of Ni content. AlCoCuFeNi and AlCoCrCuFeNi alloys prepared by selective laser melting and splat quenching were single phase structure which is due to the high cooling rate inhibiting the diffusion of atoms. The change of microstructure could also affect the mechanical properties. Thus, the effects of alloying element, processing method and temperature on the mechanical property of Cu-contained HEAs were also discussed. For instance, the strength of HEAs could be approved by adding V into the alloy or preparing alloys with additive manufacturing methods such as selective laser melting and laser powder bed fusion.