Compositionally graded CoCrFeNiTix high-entropy alloys manufactured by laser powder bed fusion: A combinatorial assessment

[摘要] A modified laser powder bed fusion (LPBF) technique was utilized to fabricate CoCrFeNi high-entropy alloy (HEA) coupon with stepwise gradation (from 0 to similar to 12 at%) in Ti, to ascertain the maximum Ti content that can be added to the HEA for enhancing its strength. The microstructure and mechanical behavior of the fabricated coupon were investigated. High-resolution scanning transmission electron microscopy show the formations of second phases including body-centered cubic, Laves, and chi phases within the face-centered cubic matrix phase. The volume fractions of all the second phases increase with the Ti content, with a concomitant enhancement in the hardness. The observation of extensive cracking in the alloy region with similar to 12 at% Ti suggests that a maximum of similar to 10 at% Ti can be added during LPBF of CoCrFeNi HEA. A detailed analysis of the contributions of various strengthening mechanisms suggests that the second phases are the dominant contributors to the observed hardening with the Ti addition. While the Laves and chi phases induce substantial hardness enhancement, they also contribute to the cracking during LPBF of the high Ti-containing HEAs. (C) 2021 Elsevier B.V. All rights reserved.

[发布日期] 2021-11-25

[关键词] High-entropy alloy;Laser powder bed fusion;Compositional grade;Nanoindentation;Phase evolution