Strengthening and fracture mechanisms of a precipitation hardening high-entropy alloy fabricated by selective laser melting
Strengthening and fracture mechanisms of a precipitation hardening high-entropy alloy fabricated by selective laser melting
复制标题
选区激光熔凝沉淀硬化高熵合金的强化和断裂机制
DOI：
10.1080/17452759.2022.2037055
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发表时间：
2022-02
影响因子：
10.6
通讯作者：
Yao-guang Wu;Xinyi Zhao;Qiang Chen;Can Yang;Mingguang Jiang;Changyong Liu;Zhen Jia;Zhangwei Chen;Tao Yang;Zhiyuan Liu
中科院分区：
文献类型：
--
作者：
Yao-guang Wu;Xinyi Zhao;Qiang Chen;Can Yang;Mingguang Jiang;Changyong Liu;Zhen Jia;Zhangwei Chen;Tao Yang;Zhiyuan Liu
摘要：采用选择性激光熔化（SLM）法制备了HEA (FeCoNi)86Al7Ti7高熵合金，并在不同温度和时间条件下进行时效处理。时效后HEA的屈服强度从710 ~ 934，再到1203 MPa显著增加。理论分析表明，时效后HEAs强度的提高主要是由共格L12析出物贡献的，而时效过程中的恢复导致位错密度的降低，从而产生软化作用。此外，塑性随非共格L21相体积分数的增加而降低。基于空洞生长模型，定性地解释了这一趋势。此外，还提出了一种新的断裂模式，即细胞间断裂，以解释断裂韧窝大小对位错细胞的强烈依赖，并通过精密的显微结构检查直接验证。研究结果为增材制造HEA提供了有效的强化方法，并提出了一种独特的断裂机制。
ABSTRACT A precipitation hardening high-entropy alloy (HEA) (FeCoNi)86Al7Ti7 was fabricated by selective laser melting (SLM) and ageing treated under different temperatures and time conditions. Yield strength of the aged HEA increases substantially from 710 to 934 and then to 1203 MPa. Theoretical analyses reveal that the coherent L12 precipitate contributes most of the improved strength for the aged HEAs, whereas recovery during ageing causes the decrease of dislocation density thus exerts a softening effect. In addition, it is found that ductility decreases with increasing volume fraction of the incoherent L21 precipitates. Based on a void growth model, the trend is qualitatively explained. Moreover, a new fracture mode, intercellular fracture, is proposed to account for the strong dependence of fracture dimple size on the dislocation cells, also directly validated by delicate microstructural examination. The findings provide an effective strengthening method and propose a unique fracture mechanism for the additively manufactured HEA.