A Novel Martensitic-Like Transformation Fe-Based Multi-principal Element Alloy

Fe65-xNi25Co5Cr5Alx (x = 0,5,10,15,20,25) multi-principal element alloys (MPEAs) were prepared by vacuum arc melting and heat-treated to systematically study the effects of Al elements and heat treatment on the microstructure and mechanical properties of Fe-based MPEAs. The results showed that with the addition of Al element, the alloy structure changed from FCC structure to FCC + B2 structure and finally to BCC + B2 spinodal structure, and the addition of Al promoted the formation of body-centered cubic structure. After heat treatment, the B2 phase got precipitated out of the FCC matrix of Al10 and Al15 alloys, Al20 alloy underwent a martensitic-like transformation, and Al25 alloy maintained the labyrinthine spinodal structure. A significant enhancement of compressive properties was found in Al20 and Al25 alloys. Among them, Fe45Ni25Co5Cr5Al20 alloy had the best room temperature compressive properties, its yield strength, fracture strength, and fracture strain that were 1292.2, 3145.2 MPa, and 42.2%, respectively, and its fracture strength and fracture strain were 1.9 times and 3.6 times of as-cast state.