Vickers Hardness Evaluation of a High-Entropy Alloy after Melting in a Boron Nitride-Coated Crucible and Subsequent Pack Carburizing

High-Entropy Alloys (HEAs) belong to a group of materials featuring combinations of at least five elements in equimolar proportions, enabling the formation of body-centered cubic (BCC) structures with high-temperature resistance, wear resistance, and high hardness. This research developed a seven-element HEA designed to achieve a BCC structure, prepared via induction furnace melting. After melting the alloy designated as L5.7, Vickers hardness was measured; subsequently, a pack carburizing heat treatment was performed to increase hardness. Two melts were conducted: the first in a high-density graphite crucible and the second in a hexagonal boron nitride (h-BN) crucible. The average hardness result for the melt performed in the BN crucible was 19.57% higher compared to the other. For this same melting condition, after carburizing, an average hardness of 1783 HV was obtained—49.71% higher than the carburized sample melted in the uncoated crucible. Based on the results, it is concluded that boron nitride (h-BN) contributed to the increase in Vickers hardness both before and after the thermochemical treatment.