Volume energy density induced grain refinement and enhanced mechanical properties of FeCoCrNiMn high-entropy alloy fabricated by selective laser melting (SLM)

Abstract

This study investigates the influence of volume energy density on the microstructure and mechanical properties of FeCoCrNiMn high-entropy alloy fabricated by selective laser melting (SLM). By systematically varying the laser processing parameters, the effects on crystal morphology, grain refinement, and mechanical performance, including porosity, tensile strength, microhardness, and wear resistance, were evaluated. The results demonstrate that lower volume energy density promotes significant grain refinement, increases the density of grain boundaries and twins, and leads to the formation of a checkerboard-like crystal structure. These microstructural features enhance the alloy’s ability to store dislocations and energy, resulting in improved yield strength and maximum tensile strength. In contrast, higher volume energy density increases porosity, grain size, and texture strength, and induces a predominantly intragranular fracture mode, which contributes to improved uniform elongation. Overall, precise control of volume energy density during SLM processing enables the optimization of grain structure and mechanical properties, achieving a desirable balance of tensile performance, strain hardening, toughness, and wear resistance in FeCoCrNiMn high-entropy alloys.