Magnesium Containing High Entropy Alloys

High Entropy alloys (HEAs) or Complex Concentrated Alloys (CCAs) or Multi-Principal Element Alloys (MPEAs) is a matter of interest to material scientists for the last two decades due to the excellent mechanical properties, oxidation and corrosion resistant behaviors. One of the major drawbacks of HEAs is their high density. Mg containing HEAs show low density compared to peers, although extensive research is required in this field. This chapter aims to include all the available information on synthesis, design, microstructures and mechanical properties of Mg containing HEAs and to highlight the contemporary voids that are to be filled in near future

Nearly full-density pressureless sintering of AlCoCrFeNi-based high-entropy alloy powders

AlCoCrFeNi is among the promising high-entropy alloys (HEAs) that possess high strength with considerable ductility. Powder sintering is one of the competitive routes for the production of HEA powders. However, sintering of HEA powders under a pressureless condition is difficult. The present work aims to produce high-density components from mechanically alloyed AlCoCrFeNi HEA powders through the pressureless sintering method. Nearly full density was achieved at 1275 °C. Sintering was performed in the presence of a viscous phase in the temperature range of 1200–1250 °C, which was confirmed through differential scanning calorimetry and dilatometric measurements. This viscous phase was found have a Cr-rich composition, detected by interrupting the sintering and quenching of the sample. The powder initially contained the BCC phase with a small fraction of FCC and other phases. During sintering, a significant fraction of the FCC phase and nanosized B2 phase were formed. Sintered sample had a hardness of 679 ± 20 Hv

Viscous flow assisted sintering of AlCoCrFeNi high entropy alloy powder

Present investigation attempts to evaluate the sintering kinetics of mechanically alloyed AlCoCrFeNi high entropy alloy powder. Dilatometric study shows an accelerated densification above 1150 °C during non-isothermal sintering. The process was characterized with an activation energy of 166 ± 13 kJ/mol. Sintering was found to be controlled by the viscous flow mechanisms and atomic diffusion of constituent elements in the melt phase. This was attributed to the formation of some Cr-rich viscous phase, which had a good wettability on the solid. Results were further confirmed by an endothermic peak during differential scanning calorimetry and the solidified phases around the grains, in the quenched microstructure