Composition design to tune the mechanical behavior of a TRIP-TWIP (CrMnFeCoNi)50 Fe50-xCrx multi-principal element alloys

Abstract

The utilization of the laser melting deposition (LMD) method to synthesize the (CrMnFeCoNi)50Fe50-xCrx (x = 5, 10, and 15 at.%) multi-principal elements alloys (MPEAs) are successfully demonstrated. It discovers that all (CrMnFeCoNi)50Fe45Cr5, (CrMnFeCoNi)50Fe40Cr10, and (CrMnFeCoNi)50Fe35Cr15 MPEAs retain a single-phase solid solution microstructure, and the in-situ structure transformation found in the matrix is ascribed to the reduction of the stability of FCC structure via appropriately tailoring constituent elements. (CrMnFeCoNi)50Fe45Cr5 MPEA exhibits the simultaneous enhancement in the plasticity (almost 100%) and the tensile strength (from 415 MPa to 470 MPa) resulting from the co-contribution of deformation-induced twining and tiny amounts of precipitation for M23C6 carbide at ambient temperature. Inversely, (CrMnFeCoNi)50Fe35Cr15 displays remarkable improvement in the tensile strength (∼ 600 MPa) at the sacrificing of the plasticity elongation (from 50% to 32%) originating from the contribution of strain-induced structure transformation. Here, the transformation-induced twinning and transformation-induced ductility are successfully achieved by tuning the stability of the constituent phases in the (CrMnFeCoNi)50Fe50-xCrx MPEAs. These discoveries not only distinctly distinguish the tensile strength and plasticity of the (CrMnFeCoNi)50Fe50-xCrx MPEAs from the corresponding CoCrFeMnNi MPEA, but also pave the way for designing and enhancing the comprehensive properties of MPEAs and other structural materials for engineering applications.