Compositionally graded CoCrFeNiTₓ high-entropy alloys manufactured by laser powder bed fusion: a combinatorial assessment
A modified laser powder bed fusion (LPBF) technique was utilized to fabricate CoCrFeNi high-entropy alloy (HEA) coupon with stepwise gradation (from 0 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 beh...
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Main Authors: | , , , , , , , , |
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Other Authors: | |
Format: | Article |
Language: | English |
Published: |
2022
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Subjects: | |
Online Access: | https://hdl.handle.net/10356/157014 |
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Institution: | Nanyang Technological University |
Language: | English |
Summary: | A modified laser powder bed fusion (LPBF) technique was utilized to fabricate CoCrFeNi high-entropy alloy (HEA) coupon with stepwise gradation (from 0 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 χ 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 ~12 at% Ti suggests that a maximum of ~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 χ phases induce substantial hardness enhancement, they also contribute to the cracking during LPBF of the high Ti-containing HEAs. |
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