Laser powder bed fusion of high-entropy alloy particle-reinforced stainless steel with enhanced strength, ductility, and corrosion resistance

In additive manufacturing of metal matrix composites, it is difficult to ensure high strength as well as high ductility simultaneously. In this study, a FeCoNiCr high-entropy alloy was used as the strengthening phase to improve the performance of austenitic stainless steel processed via laser powder bed fusion. The microstructure of the as-printed parts was composed of high-entropy alloy nanoparticles, a solid solution matrix, and high-density dislocations. The strengthening effect caused by the microstructures resulted in a tensile strength of 627 MPa with a maximum elongation of 50%. The semi-obstructive effect of the interface on the dislocations improved the ductility, as proved through molecular dynamics analysis. The Cr, Ni, and Co elements in the high-entropy alloy melted into the stainless-steel matrix, facilitating the formation of a passive film; this improved the corrosion resistance of the composite. Thus, simultaneous improvements in strength, ductility, and corrosion resistance of the stainless-steel composites were realized. The composites inherited the performance characteristics of high-entropy alloys. This research also provides a new strategy to select the strengthening phase for composite materials. High-performance high-entropy alloy particles with lattice structures and element types similar to the stainless steel matrix have substantial potential to be used as strengthening phases.