材料科学
选择性激光熔化
等轴晶
极限抗拉强度
微观结构
合金
针状的
硬化(计算)
位错
复合材料
冶金
加工硬化
应变硬化指数
图层(电子)
作者
Xintian Wang,Xingyu Pan,Pengyue Sun,Chunlei Qiu
标识
DOI:10.1016/j.msea.2021.142285
摘要
In this study, 4 at.% Ti–48Al–2Cr–2Nb (TiAl) powder particles were added into CoCrFeMnNi high entropy alloy (HEA) and processed by selective laser melting (SLM) followed by hot isostatic pressing and ageing with the aim of enhancing its strengths. It was found that the as-developed HEA-TiAl sample shows a complex microstructure which is composed of near-equiaxed γ grains embedded with long-range ordered (LRO) L12 domains, various intragranular precipitates including Al2O3, B2, Heusler particles and γ-TiAl particles and grain boundary precipitates such as σ. With such a unique microstructure, the samples show remarkably enhanced 0.2% yield strength and significantly improved ultimate tensile strength and strain hardening rates. Precipitates such as Al2O3, Heusler and σ were found to have acted as effective dislocation motion obstacles. Dislocations tended to cut through the LRO L12 domains by forming stacking faults with a number of them intersecting to form immobile Lomer-Cottrell locks which are beneficial for strain hardening.
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