Effect of heat treatment on mechanical and corrosion properties of an Al0.8CrFe2Ni2 alloy processed by laser powder bed fusion

Abstract

This study presents an Al0.8CrFe2Ni2 high entropy alloy processed by laser powder bed fusion using prealloyed powder. Heat treatment of the near-single-phase face-centered-cubic microstructure, found in the as-built material, led to a fine dual-phase microstructure consisting of face-centered-cubic grains and Al-, Ni-rich body-centered-cubic B2 precipitates. Microstructure characterization, mechanical and corrosion testing revealed the effect of heat treatment on the properties of the novel alloy. The results suggested that tailoring the mechanical properties is possible with heat treatment, by controlling the precipitate size. Refinement of the precipitates led to enhanced strength without significant ductility loss. Corrosion tests in 3.5 % NaCl solution showed that the as-built samples provided an overall better corrosion resistance when compared to heat-treated samples. The presence of the precipitates enhanced the formation of micro-galvanic cells and influenced the corrosion behavior of the alloy in the heat-treated condition.