Superior low temperature mechanical properties and microstructure of (NiCoCr)95V5 medium entropy alloy

Abstract

NiCoCr, as a model medium entropy alloy has been investigated extensively in the past decades. To further improve the mechanical properties of NiCoCr, there are mainly two methods. One is thermal-mechanical treatment. The other is to add some proper alloying elements to introduce second phase to fabricate the precipitate strengthening medium entropy alloys. Inspired by this, a superior medium entropy alloy (NiCoCr)95V5 was successfully fabricated by cold rolling and subsequent two-step annealing in this study. The strength and plasticity product exceeds 86 GPa·% that is comparable to the currently reported high-performance medium and high entropy alloys. The microstructure characterizations indicate that the dislocation slip and interacting with high density nanoscale precipitates, the initiation of primary and secondary deformation twinning which further segmenting the grains are the main reasons for such high properties. This work enriches the design and development of medium and high entropy alloys with high-strength and high plasticity.