Heterogeneous structure-induced strength-ductility synergy by partial recrystallization during friction stir welding of a high-entropy alloy

• Published in: Materials & design Vol. 197; p. 109238
• Main Authors: Lin, Po-Ting, Liu, Hung-Chi, Hsieh, Po-Ying, Wei, Cheng-Yu, Tsai, Che-Wei, Sato, Yutaka S., Chen, Shih-Che, Yen, Hung-Wei, Lu, Nian-Hu, Chen, Chih-Hsuan
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.01.2021; Elsevier
• Subjects: Friction stir welding; Heterogeneous structure; High-entropy alloys; Mechanical properties; Recrystallization; High-entropy alloys; Mechanical properties; Heterogeneous structure; Friction stir welding; Recrystallization
• ISSN: 0264-1275; 1873-4197
• DOI: 10.1016/j.matdes.2020.109238

To apply high-entropy alloys (HEAs) for extensive advanced structural uses, their welding properties should be well understood. In this study, Al0.3CoCrCu0.3FeNi HEA was butt welded by friction stir welding (FSW). The fine-grained partially recrystallized microstructure in the stir zone gave rise to a high tensile yield strength of 920 MPa with an elongation of 37%. By microstructural observation, the excellent mechanical properties of the stir zone material were attributed to the partially recrystallized heterogeneous structure, with which the synergetic strengthening improved the strength of the HEA with considerably less trade-off in its ductility. This unique phenomenon was unprecedented in any other friction-stir welded conventional alloys and was credited to the low stacking-fault energy and the high grain growth activation energy of the HEA. This work suggests that FSW can not only produce good HEA welds but serve as a special processing technique to enhance mechanical properties of HEAs. [Display omitted] •The partially recrystallized heterogeneous microstructure produced by friction stir welding leads to strong and ductile high-entropy alloys.•Friction stir welding can serve as a novel processing technique for high-entropy alloys provided their conduciveness to heterogeneities.•Low stacking fault energy and high grain growth activation energy facilitate the formation of heterogeneous structures during friction stir welding.