Evolution of microstructure, mechanical and corrosion properties of AlCoCrFeNi high-entropy alloy prepared by direct laser fabrication
Evolution of microstructure, mechanical and corrosion properties of AlCoCrFeNi high-entropy alloy prepared by direct laser fabrication
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DOI：
10.1016/j.jallcom.2016.10.138
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发表时间：
2017-02-15
影响因子：
6.2
通讯作者：
Wu, Xinhua
中科院分区：
文献类型：
--
作者：
Wang, Rui;Zhang, Kai;Wu, Xinhua
高熵合金（HEA）是一类新兴的工程材料，在高温应用方面显示出巨大的潜力。这些多元合金大多通过电弧熔炼制造。在本研究中，采用直接激光制造（DLF）在优化的操作参数下制备 AlCoCrFeNi 高熵合金。研究了沉积态合金以及在600℃、800℃、1000℃和1200℃时效168h的样品的物相、显微组织、力学性能和腐蚀性能。结果表明，沉积过程中的高冷却速率抑制了 FCC 相的形成，导致沉积样品几乎形成单一的 B2 固溶体结构。在800℃、1000℃和1200℃时效后，显微组织呈现晶间针状和板状FCC相析出物以及沿晶界的壁状FCC相析出物。由于 FCC 相比 B2 相软，时效过程中 FCC 相的形成导致压缩屈服强度降低，同时延展性增强。富Fe-Cr的FCC相与富Al-Ni的B2基体之间的电位差意味着该合金容易受到电偶腐蚀，其中B2基体优先腐蚀。 (C) 2016 Elsevier B.V. 保留所有权利。
High entropy alloy (HEA) is an emerging class of engineering materials that shows promising potential for high temperature applications. These multi-component alloys are mostly fabricated by arc melting. In this study, direct laser fabrication (DLF) is utilized to prepare AlCoCrFeNi high entropy alloy at optimized operation parameters. The phase, microstructure, mechanical and corrosion properties of as-deposited alloy as well as samples aged at temperatures of 600 degrees C, 800 degrees C, 1000 degrees C and 1200 degrees C for 168 h have been investigated. The results show that high cooling rate during deposition inhibits the formation of FCC phase, leading to a nearly single B2 solid solution structure for as-deposited sample. After ageing at 800 degrees C, 1000 degrees C and 1200 degrees C, the microstructures exhibit intergranular needle-like and plate-like FCC phase precipitates and wall shaped FCC phase precipitates along grain boundaries. As the FCC phase is softer than B2 phase, the formation of the FCC phase during ageing results in reduced compressive yield strength accompanied with enhanced ductility. The potential difference between Fe-Cr rich FCC phase and Al-Ni rich B2 matrix means the alloy is susceptible to galvanic corrosion, with the B2 matrix corroding preferentially. (C) 2016 Elsevier B.V. All rights reserved.