Remarkable strength of a non-equiatomic Co29Cr29Fe29Ni12.5W0.5 high-entropy alloy at cryogenic temperatures

MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING

卷:818

Article

Wei, Chengbin¹  Lu, Yiping¹  Du, Xinghao²  Li, Tingju¹  Wang, Tongmin¹  Liaw, Peter K.³ 

[1] Dalian Univ Technol, Sch Mat Sci & Engn, Key Lab Solidificat Control & Digital Preparat Te, Dalian 116024, Peoples R China

[2] Shenyang Aerosp Univ, Sch Mat Sci & Engn, Shenyang 110136, Peoples R China

[3] Univ Tennessee, Dept Mat Sci & Engn, Knoxville, TN 37996 USA

关键词: High-entropy alloys;    Dislocation;    Stacking fault;    Phase transformation;    Mechanical properties;   

DOI  :  10.1016/j.msea.2021.141446

来源: Elsevier

【 摘 要 】

A non-equiatomic Co29Cr29Fe29Ni12.5W0.5 high-entropy alloy (HEA) strengthened by two-step rolling was fabricated, and its microstructure evolution and tensile behavior at cryogenic temperatures were investigated. When the temperature decreases from 293 K to 173 K, the yield strength increases from 640 MPa to 1017 MPa. At 77 K, an outstanding strength-ductility synergy can be observed, with a yield strength of 1.33 GPa and an excellent ductility of 46%. Prior to tensile testing, the annealed alloy largely has a single face-centered cubic (FCC) structure, while a hexagonal-close packed (HCP) phase is formed in the cryogenically tensile-fractured alloy along the {111} planes. Such high yield strength and tensile plasticity values at cryogenic temperatures are extremely rare in HEAs and even in metal alloys. The deformation micro-mechanism was carefully investigated by a transmission electron microscope, and the results indicated that the cryogenic-temperature properties could be attributed to stacking faults (SFs) and the phase having a hexagonal-close-packed (HCP) structure. The densities of the SFs and the HCP laths have a considerable influence on the work-hardening behavior.

【 授权许可】

Free