Improving ductility in dual-phase FeNi2Al medium-entropy alloy through rapid solidification-induced expansion of Interface transition zones

Multi-principal element alloys (MPEAs), renowned for their exceptional properties, have garnered significant attention in materials science. However, their limited ductility has restricted their widespread applications. In our investigation, the toughness of a Co-free dual-phase (B2 + L12) FeNi2Al medium-entropy alloy was improved by manipulating the microstructure through rapid solidification. A significant improvement in the total tensile elongation (TE) and ultimate tensile strength (UTS) of the as-cast FeNi2Al alloy at 253 K compared to the as-melted counterpart can be observed. Specifically, the as-cast alloy exhibited enhanced values of 13.1% for TE and 1111.0 MPa for UTS, whereas the as-melted FeNi2Al alloy displayed 6.1% for TE and 1176.2 MPa for UTS. This represents a remarkable 114.1% increase in TE, with only a marginal 6.3% decrease in UTS. Microstructure analysis indicates that augmenting the L12 phase content, refining the grain size, and fostering interfacial transition zones between the B2 and L12 phases, all achieved through rapid solidification, collectively contributed to the improved ductility of the FeNi2Al alloy. This work presents an effective and promising strategy for enhancing the ductility of multi-phase MPEAs, offering new opportunities for their broader application in various industries. •Excellent strength/ductility of FeNi2Al medium-entropy alloy are fabricated by direct-chilling casting at 253 K.•Compared to the as-melt alloy, the smaple cast at 253 K, TE increases to 13.1%, and UTS only decreases to 1111.0 MPa.•The interfacial transition zone between the B2 phase and the L12 phase in the FeNi2Al has a great influence on the toughness.