A ductile high entropy alloy strengthened by nano sigma phase

• Published in: Intermetallics Vol. 122; p. 106813
• Main Authors: Zhang, Lu, Huo, Xiaofeng, Wang, Anguo, Du, Xinghao, Zhang, Li, Li, Wanpeng, Zou, Naifu, Wan, Gang, Duan, Guosheng, Wu, Baolin
• Format: Journal Article
• Language: English
• Published: Barking Elsevier Ltd 01.07.2020; Elsevier BV
• Subjects: Crack propagation; Deformation; Ductility; Face centered cubic lattice; Hardening rate; High entropy alloy; High entropy alloys; Intermetallic phase; Nanoparticles; Precipitation hardening; Sigma phase; Strain hardening; Strength; Work hardening; Work hardening; High entropy alloy; Ductility; Intermetallic phase; Precipitation hardening; Strength
• ISSN: 0966-9795; 1879-0216
• DOI: 10.1016/j.intermet.2020.106813

A nanoscale sigma (σ) phase strengthened Co34.5Cr30Ni26.5Al5.4W3.6 (at, %) high entropy alloy was prepared and showed high strength and ductility. Dual phase microstructure that comprises face-centered cubic (FCC) matrix and nanoscale σ particles was obtained after thermomechanical procedures. The excellent ductility is attributed to its high strain hardening exponent FCC matrix that strongly favors uniform deformation and prevents crack propagation. The alloy shows an extremely high strain hardening rate and strength due to the interactions between the σ particles, deformation twins and dislocations. The design concept of “deformation twins + nano particles” should be considered for the design of additional double-high (strength and ductility) FCC HEAs in future work. •A new sigma phase strengthened HEA was design.•The HEA possess outstanding strength and ductility.•The detailed strain hardening mechanism was studied.•A new design idea of double-high HEAs was proposed.