Selective laser melting of the Al0.3CoCrFeNiCu high-entropy alloy: Processing parameters, microstructure and mechanical properties

The as-printed Al0.3CoCrFeNiCu high-entropy alloy (HEA) was fabricated from gas-atomized powders by selective laser melting (SLM) with the tailored printing parameters. The processing parameters, microstructural characteristics, mechanical properties and formed defects of the SLM-processed Al0.3CoCrFeNiCu HEA were examined in detail. The SLM-processed HEAs presented a simple disordered face centered cubic solid solution with columnar grains growing along the building direction and exhibiting a (001) preferred orientation. Dendritic-segregation, a common phenomenon occurring in as-cast counterparts was eliminated, thus providing a significant method to form a single-phase solid solution. The cellular structure in the columnar grains germinated perpendicular to the boundary of molten pools. In addition, dislocations induced by internal stress were observed. Accordingly, the SLM-processed Al0.3CoCrFeNiCu HEA exhibited superior microhardness , compressive strength. Finally, two types of defects were found in this SLM alloy, including irregular holes and hot cracks. The latter occurring on solid-liquid interface of molten pool were retarded by grain boundaries and then turned into muti-branches. Nevertheless, no crack-free sample could be prepared even though the printing parameters were optimized to achieve a high relative density of 99.08%, indicating this HEA was not suitable for SLM technology to prepare. (C) 2022 The Authors. Published by Elsevier Ltd.