High entropy alloys (HEA) have been one of the most attractive groups of materials for researchers in the last several years. Since HEAs are potential candidates for many (e.g., refractory, cryogenic, medical) applications, their properties are studied intensively. The most frequent method of HEA synthesis is arc or induction melting. Powder metallurgy is a perspective technique of alloy synthesis and therefore in this work the possibilities of synthesis of HfNbTaTiZr HEA from powders were studied. Blended elemental powders were sintered, hot isostatically pressed, and subsequently swaged using a special technique of swaging where the sample is enveloped by a titanium alloy. This method does not result in a full density alloy due to cracking during swaging. Spark plasma sintering (SPS) of mechanically alloyed powders resulted in a fully dense but brittle specimen. The most promising result was obtained by SPS treatment of gas atomized powder with low oxygen content. The microstructure of HfNbTaTiZr specimen prepared this way can be refined by high pressure torsion deformation resulting in a high hardness of 410 HV10 and very fine microstructure with grain size well below 500 nm.

CTU Prague Faculty of Mechanical Engineering Karlovo Náměstí 13 121 35 Praha 2 Czech Republic

Department of Materials Science and Engineering POSTECH Pohang 790 784 Korea

Faculty of Materials Science and Technology VŠB Technical University of Ostrava 17 Listopadu 15 708 33 Ostrava 8 Cech Republic

Faculty of Mathematics and Physics Charles University 180 00 Praha 8 Czech Republic

Institute of Plasma Physics CAS 182 00 Praha 8 Czech Republic

UJP PRAHA a s Nad Kamínkou 1345 156 10 Prague Zbraslav Czech Republic

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Special Issue: Mechanical Properties in Progressive Mechanically Processed Metallic Materials