Microwave assisted synthesis of Si-modified Mn25FexNi25Cu(50−x) high entropy alloys

•Microwave heating of pure metal powders is used to prepare high entropy alloys.•Minimum losses of the most oxygen-reactive elements occurred under Ar flux.•Small Si addition to Mn25FexNi25Cu(50−x) alters microstructure and increases hardness.

Rapid microwave heating at 2450 MHz of metallic powders mixtures compacts was performed under Ar flux in a single mode applicator in order to produce Si-modified Mn25FexNi25Cu(50−x), (x=25, 30, 35, 40) high entropy alloys. Microwave heating was conducted in presence of a SiC auxiliary absorber, so that the compacts are subjected to both direct heating by microwave absorption and indirect heating by the auxiliary absorber. Due to the extremely rapid processing times, including the cooling stage, depletion of the most oxygen-reactive elements was moderate, considering the not perfectly protective atmosphere used. FCC solid solutions have been obtained and the role of Si is discussed as a microstructure modifier and as increaser of the microhardness.