Manipulating Stacking Fault Energy to Achieve Crack Inhibition and Superior Strength-Ductility Synergy in an Additively Manufactured High-Entropy Alloy

Pengda Niu; Ruidi Li; Kefu Gan; Zhiqi Fan; Tiechui Yuan; Changjun Han

doi:10.1002/adma.202310160

Manipulating Stacking Fault Energy to Achieve Crack Inhibition and Superior Strength-Ductility Synergy in an Additively Manufactured High-Entropy Alloy

Adv Mater. 2024 Mar 15:e2310160. doi: 10.1002/adma.202310160. Online ahead of print.

Authors

Pengda Niu¹, Ruidi Li¹, Kefu Gan², Zhiqi Fan³, Tiechui Yuan¹, Changjun Han⁴

Affiliations

¹ National Key Laboratory of Science and Technology for High-Strength Structural Materials, State Key Laboratory of Powder Metallurgy, Central South University, Changsha, 410083, P. R. China.
² School of Materials Science and Engineering, Central South University, Changsha, 410083, P. R. China.
³ State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an, 710049, P. R. China.
⁴ School of Mechanical and Automotive Engineering, South China University of Technology, Guangzhou, 510641, P. R. China.

PMID: 38489830
DOI: 10.1002/adma.202310160

Abstract

Additive manufacturing (AM) is a revolutionary technology that heralds a new era in metal processing, yet the quality of AM-produced parts is inevitably compromised by cracking induced by severe residual stress. In this study, a novel approach is presented to inhibit cracks and enhance the mechanical performances of AM-produced alloys by manipulating stacking fault energy (SFE). A high-entropy alloy (HEA) based on an equimolar FeCoCrNi composition is selected as the prototype material due to the presence of microcracks during laser powder bed fusion (LPBF) AM process. Introducing a small amount (≈2.4 at%) of Al doping can effectively lower SFE and yield the formation of multiscale microstructures that efficiently dissipate thermal stress during LPBF processing. Distinct from the Al-free HEA containing visible microcracks, the Al-doped HEA (Al_0.1CoCrFeNi) is crack free and demonstrates ≈55% improvement in elongation without compromising tensile strength. Additionally, the lowered SFE enhances the resistance to crack propagation, thereby improving the durability of AM-printed products. By manipulating SFE, the thermal cycle-induced stress during the printing process can be effectively consumed via stacking faults formation, and the proposed strategy offers novel insights into the development of crack-free alloys with superior strength-ductility synergy for intricate structural applications.

Keywords: additive manufacturing; crack free; high‐entropy alloy; laser powder bed fusion; stacking fault energy.

Abstract

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