Microstructural Evolution of Co35Cr25Fe30Ni10 TRIP Complex Concentrated Alloy with the Addition of Minor Cu and Its Effect on Mechanical Properties

The influences of minor Cu addition (2 and 4 at.%) on the microstructural evolution and room-temperature mechanical property of metastable Co35Cr25Fe30Ni10 are systemically investigated in the present study. The results indicate that the thermally induced hexagonal close-packed (HCP) phase is absent when Cu was added, due to the increase in stacking fault energy (SFE). The 2%-Cu-added alloys showed the largest total elongation of 69% among the three alloys. With the addition of Cu content reaching 4 at.%, heterogeneous grain structures composed of coarse grains (~ 9 μm) and fine grains (~ 4 μm) and Cu-rich precipitates near the grain boundary are observed, showing the highest yield strength. Additionally, the segregation state of Cu was quantitatively characterized by electron probe microanalysis (EPMA). And effects of Cu addition on microstructures and tensile properties of (Co35Cr25Fe30Ni10)100-xCux are also discussed. The findings are beneficial to comprehensively understand the Cu-containing complex concentrated alloys.