|About this Abstract
||1st World Congress on High Entropy Alloys (HEA 2019)
||High Entropy Alloys 2019
||P25: Sintering of HfNbTaTiZr Alloy
||Frantisek Lukac, Monika Vilémová, Radek Mušálek, Štefan Csáki, Jan Čížek, Jakub Čížek
|On-Site Speaker (Planned)
Refractory alloys are often produced by sintering process due to the advantage of relatively low processing temperature and time and high heating rates. Mechanical properties of powder metallurgy products sintered by spark plasma sintering method used in this work are drastically different from other processing routes due to smaller grain size, different phase composition, porosity, oxide content and microstructure depending on powder preparation. Firstly, single phase HfNbTaTiZr alloy with various grain size was produced from gas atomized powder using various sintering parameters. Secondly, sintering of mechanically alloyed powder produced by high energy ball milling process resulted in disintegration of high entropy bcc phase into marble-like microstructure of nanocrystalline sized grains comprised of different intermetallic phases. High deformation induced in this powder acts as diffusion accelerator and therefore thermal treatment during sintering produces promising properties. Besides quantitative phase composition analysis, defects concentration measured by positron annihilation is emphasized in this work.