Regulation of chemical microenvironment to overcome strength-ductility trade-off in FeCrVTiSix high-entropy alloys coating

Abstract

Developing metallic materials with both high strength and ductility is an enormous challenge in the field of materials science and engineering due to commonly known “strength-ductility trade-off”. In this work, we proposed a regulation strategy of the chemical microenvironment through changing valence electron concentration (VEC) to achieve simultaneous improvement of the strength and ductility of metallic materials. Taking FeCrVTiSix system as a proof-of-concept model, we first predicted the influence of Si on the chemical microenvironment through density functional theory calculations. These calculations unveiled that Si atoms effectively modify the bonding state among alloy elements, resulting in an enhancement of the strength within the FeCrVTi alloy system while maintaining its ductility. Building upon this insight, we successfully synthesized FeCrVTiSix alloys coating using laser cladding techniques. Subsequent tests, including nanoindentation, Vickers hardness, and tensile assessments, unequivocally demonstrated that the introduction of Si significantly increases the strength of the alloy while maintaining its ductility. Si atoms play a pivotal role in modulating the slip behavior of high-entropy alloys (HEAs) by reshaping the chemical microenvironment, thus enabling the elevation of strength in HEAs while preserving ductility. This work provides a novel approach for designing HEAs that effectively circumvent the “strength-ductility trade-off”, potentially broadening the horizons of engineering applications for HEAs coating.