Influence of Cr removal on the microstructure and mechanical behaviour of a high-entropy Al_0.8Ti_0.2CoNiFeCr alloy fabricated by powder metallurgy

ABSTRACT

We report a systematic study on the influence of Cr removal on the microstructure and mechanical behaviour of an ultra-fine grained (UFG) high-entropy alloy (HEA), Al_0.8Ti_0.2CoNiFeCr, fabricated via spark plasma sintering (SPS) of mechanically alloyed (MA’ed) powders from constituent elemental powders. The MA’ed Al_0.8Ti_0.2CoNiFeCr powders consist principally of a BCC phase (∼85 vol.-%) with a small amount of FCC phase (∼15 vol.-%), whereas the MA’ed Al_0.8Ti_0.2CoNiFe powders present similar phases to those in the MA’ed Al_0.8Ti_0.2CoNiFeCr powders. Interestingly, the SPS processed UFG Al_0.8Ti_0.2CoNiFeCr alloy contains mostly an FCC phase (∼78 vol.-%) and some BCC phase (∼22 vol.-%); in contrast, the SPS processed UFG Al_0.8Ti_0.2CoNiFe alloy consists of a slightly enriched BCC phase (∼53 vol.-%) and an FCC phase (∼47 vol.-%). In addition, the SPS processed Al_0.8Ti_0.2CoNiFe alloy exhibits slightly higher yield strength, compressive strength and hardness but lower plasticity than those of the SPS processed Al_0.8Ti_0.2CoNiFeCr alloy.

Special theme block on high entropy alloys, guest edited by Paula Alvaredo Olmos, Universidad Carlos III de Madrid, Spain, and Sheng Guo, Chalmers University, Gothenburg, Sweden.

KEYWORDS:

• High-entropy alloys
• powder metallurgy
• microstructure
• mechanical behaviour

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes on contributors

Zhiqiang Fu is a postdoctoral scholar at University of California, Irvine.

Weiping Chen is a distinguished professor at South China University of Technology.

Zhenfei Jiang is a PhD student at South China University of Technology.

Benjamin E. MacDonald is a PhD student at University of California, Irvine.

Yaojun Lin is a professor at Wuhan University of Technology.

Fei Chen is a professor at Wuhan University of Technology.

Lianmeng Zhang is a distinguished professor at Wuhan University of Technology.

Enrique J. Lavernia is a distinguished professor at University of California, Irvine.

ORCID

Lianmeng Zhang http://orcid.org/0000-0002-0653-2230

Additional information

Funding

The authors acknowledge the financial support from the Opening Project of Guangdong Key Laboratory for Advanced Metallic Materials processing, South China University of Technology (GJ201601) and from the US Army Research Office (W911NF-16-1-0269), and Alexander von Humboldt Research Award for Senior Researchers.