High-entropy M2AlC-MC (M=Ti, Zr, Hf, Nb, Ta) composite: Synthesis and microstructures.

A high-entropy M 2 AlC-MC (M=Ti, Zr, Hf, Nb, Ta) composite was produced by reactive hot pressing using Ti, Zr, Hf, Nb, Ta, Al, and graphite as raw materials. Successful solution of the five transition metals in both hexagonal M 2 AlC and cubic MC was confirmed by XRD, SEM, atom-resolved STEM and EDS elemental analyses. The high-entropy M 2 AlC shows larger delocalization of atoms and higher lattice strain than the high-entropy MC along with considerable amount of Al vacancies. The formation mechanism of the high-entropy composite has been discussed. The Vickers hardness of the composite is measured to be 11.1 ± 1.1 GPa. Image, graphical abstract [ABSTRACT FROM AUTHOR]