Hot Pressing Process Optimization Of High Entropy Alloys Using Elemental Powder Mixtures

This study investigated the hot pressing of three distinct high entropy alloy (HEA) powder compositions, namely CrMo0.5NbTa0.5TiZr (named HEA-01), AlCrMoNbTi (HEA-02) and AlCrFeNiTi (HEA-03). The experimental design focused on varying temperature and dwell time, while pressure remained constant. Density was adopted as a response, which was assessed through both quantitative (using Archimedes density test with theoretical densities as a reference) and qualitative analysis (via microstructural examination). Subsequent hardness testing was also performed. It was observed that for HEA-01 and 03, fully dense parts were achieved in conditions where reactions between the constituents occurred, which resulted in material loss via “squeezing” phenomenon (i.e., when excess material is expelled from the die during pressing). HEA-02 achieved densities above 99% without major squeezing or melting being reported. In any case, the observed microstructure was considered heterogeneous. Depending on processing conditions, HEA-01 and HEA-02 reached hardness values of 341 ± 25 and 429 ± 37 HV10, respectively, while HEA-03 was measured at 525 ± 25 HV10.