Enhanced strength-ductility synergy in a Ta-doped CoCrNi medium-entropy alloy with a dual heterogeneous structure
Enhanced strength-ductility synergy in a Ta-doped CoCrNi medium-entropy alloy with a dual heterogeneous structure
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DOI：
10.1016/j.msea.2022.144293
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发表时间：
2022-11
期刊：
影响因子：
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通讯作者：
Dingfeng Xu;Haitao Zhang;Mingliang Wang;Yiping Lu;Xiaohu Chen;Zheng Ren
中科院分区：
文献类型：
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作者：
Dingfeng Xu;Haitao Zhang;Mingliang Wang;Yiping Lu;Xiaohu Chen;Zheng Ren
CoCrNi中熵合金（MEA）因其具有良好的综合性能而备受关注。然而，CoCrNi合金的室温屈服强度低是其工程应用的主要障碍。为此，本研究提出了一种通过调整由热机械加工调节的异质沉淀物产生的异质晶粒来强化 CoCrNi MEA 的策略。具体而言，设计并开发了具有双异质结构的Ta掺杂CoCrNi MEA（(CoCrNi)98Ta2）。所得 (CoCrNi)98Ta2 合金表现出~1200 MPa 的高屈服应力、~1500 MPa 的极限拉伸应力，并具有~33% 的高断裂伸长率。 (CoCrNi)98Ta2合金优异的力学性能归因于异质变形诱导(HDI)硬化，它在变形过程中发挥了重要作用。 HDI 应力增强的微观结构起源是通过大量变形孪晶动态增强异质晶粒结构的结果。
The CoCrNi medium-entropy alloy (MEA) has attracted much attention owing to its promising comprehensive properties. However, the low yield strength of the CoCrNi alloy at room temperature is a major hurdle in its engineering application. In this pursuit, the present study proposed a strategy for strengthening the CoCrNi MEA by tailoring the heterogeneous grains resulting from heterogeneous precipitates regulated by thermo-mechanical processing. Specifically, a Ta-doped CoCrNi MEA ((CoCrNi)98Ta2) with a dual heterogeneous structure was designed and developed. The resulting (CoCrNi)98Ta2alloy exhibited a high yield stress of ∼1200 MPa, an ultimate tensile stress of ∼1500 MPa, and possessed a high fracture elongation of ∼33%. The excellent mechanical properties of the (CoCrNi)98Ta2alloy were attributed to the hetero-deformation induced (HDI) hardening, which played an important role during the deformation. The microstructural origin of the enhanced HDI stress was a result of the dynamically reinforced heterogeneous grain structure through numerous deformation twins.