Influence of Al content on microstructure and nanoindentation of selective laser melting AlxCoCrFeNi (x=0.3, 0.5, 0.7, 1.0)

DENG Cao; LI Ruidi; YUAN Tiechui; NIU Pengda

doi:10.11868/j.issn.1001-4381.2021.000737

Cailiao gongcheng (Jun 2022)

Influence of Al content on microstructure and nanoindentation of selective laser melting AlxCoCrFeNi (x=0.3, 0.5, 0.7, 1.0)

DENG Cao,
LI Ruidi,
YUAN Tiechui,
NIU Pengda

Affiliations

DENG Cao: State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China
LI Ruidi: State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China
YUAN Tiechui: State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China
NIU Pengda: State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China

DOI: https://doi.org/10.11868/j.issn.1001-4381.2021.000737
Journal volume & issue: Vol. 50, no. 6
pp. 27 – 35

Abstract

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AlxCoCrFeNi(x=0.3,0.5,0.7,1.0)high-entropy alloy was fabricated by selective laser melting (SLM),and pre-alloyed powder was prepared by gas atomization.The phase composition, microstructure, hardness, Young’s modulus and creep curve of AlxCoCrFeNi were comprehensively analyzed through X-ray diffractometer, scanning electron microscope and nanoindentation experiments, respectively. The influence of Al content on the microstructure and nanoindentation of AlxCoCrFeNi was discussed.The results show that Al0.3CoCrFeNi and Al0.5CoCrFeNi are FCC structure, while Al0.7CoCrFeNi and Al1.0CoCrFeNi are BCC/B2 structure. The microstructure of Al0.3CoCrFeNi and Al0.5CoCrFeNi are mainly composed of equiaxed crystals, while Al0.7CoCrFeNi and Al1.0CoCrFeNi are mainly composed of columnar crystals. It indicates that the content of Al has great influence on the microstructure of AlxCoCrFeNi high-entropy alloy.With the increase of Al content, defects such as pores and cracks in the specimens increase. There is no obvious molten pool morphology observed in Al0.3CoCrFeNi and Al0.5CoCrFeNi. The residual stress increases with the increase of Al content. The hardness and Young’s modulus of the samples were measured. It was found that with the increase of Al content,the hardness of the sample increases from 447HV to 567HV.The Young’s modulus of Al0.3CoCrFeNi is about 273 GPa, and Al0.5CoCrFeNi is about 233 GPa,while Al0.7CoCrFeNi and Al1.0CoCrFeNi are about 240 GPa and 242 GPa,respectively. The changes in hardness and Young’s modulus are mainly related to the microstructure and phases of specimens. Different from the traditional creep curve, the creep curve of AlxCoCrFeNi includes only two stages, which are instantaneous creep and steady-state creep. The creep mechanism is mainly dislocation creep. Among the samples, Al0.7CoCrFeNi has the best creep resistance. Al0.3CoCrFeNi has the best print formability, with the yield strength of 702 MPa, and the elongation is 27.5%.

Published in Cailiao gongcheng

ISSN: 1001-4381 (Print)
Publisher: Journal of Materials Engineering
Country of publisher: China
LCC subjects: Technology: Electrical engineering. Electronics. Nuclear engineering: Materials of engineering and construction. Mechanics of materials
Website: http://jme.biam.ac.cn/CN/1001-4381/home.shtml

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