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定向凝固AlCoCrCuFeNi高熵合金的组织与力学性能
Microstructure and Mechanical Properties of Directionally Solidified AlCoCrCuFeNi High-entropy Alloy
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- DOI:
- 作者:
- 邓 妮，闫育洁，梁 航，魏 晨，贺一轩，王 军
DENG Ni, YAN Yujie, LIANG Hang, WEI Chen, HE Yixuan, WANG Jun
- 作者单位:
- 西北工业大学 凝固技术国家重点实验室，陕西 西安 710072
State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi'an 710072, China
- 关键词:
- 高熵合金；定向凝固；组织演变；Cu 偏析；硬度
high-entropy alloy; directional solidification; microstructure evolution; Cu segregation; hardness
- 摘要:
- 以 AlCoCrCuFeNi 高熵合金为研究对象，研究了不同抽拉速度下定向凝固组织的演变规律，Cu 偏析及力学
性能。 结果表明：定向凝固 AlCoCrCuFeNi 高熵合金仍然为稳定的 BCC 和 FCC 两种晶体结构，微观组织由富 FeCoCr
相，富 AlNi 相和富 Cu 相组成。 随着抽拉速度增大，所获得的凝固组织由粗大的树枝晶逐渐演变为细长的层状树枝晶，
枝晶臂间距显著减小。 不同抽拉速度下，富 Cu 相都偏析于枝晶间，其在富 FeCoCr 相边界处形成不连续的锯齿状分布，
且在富 AiNi 相中形成富 Cu 沉淀。随着抽拉速度增大，富 Cu 沉淀相由亚微米级转变为纳米级，富 Cu 相中的 Cu 原子浓
度下降。 合金中不同区域组织的显微维氏硬度差异随抽拉速度增大而减小，平均显微维氏硬度从 358 HV 增加到
375 HV。
The effect of different drawing rates on microstructure, Cu segregation and mechanical properties of AlCoCrCuFeNi high-entropy alloy prepared by directional solidification was studied. The results show that the directionally solidified AlCoCrCuFeNi high-entropy alloy still has two simple BCC and FCC crystal structures, and its microstructure is composed of FeCoCr-rich, AlNi-rich and Cu-rich phases. With the increase of drawing rate, the solidification microstructure gradually changes from coarse dendrite to thin lamellar-dendrite, and the dendrite arm spacings decrease significantly. Under different drawing rates, the Cu-rich phase is segregated between dendrites and discontinuous zigzag distribution is formed at the boundary of FeCoCr-rich phase, and Cu-rich precipitate is formed in AlNi-rich phase. With the increase of the drawing rate, the Cu-rich precipitate changes from submicron to nanometer scale, and the concentration of Cu atoms in the Cu-rich phase decreases. The microhardness difference of different locations in the alloy decreases with the increase of drawing rate, and the average microhardness increases from 358 HV to 375 HV.