Effect of heat treatment on microstructure and mechanical properties of as-cast AlCoCrFeNi2.1 eutectic high entropy alloy

In this work, the effect of heat treatment on the microstructure and mechanical properties of as-cast AlCoCrFeNi2.1 eutectic high entropy alloy (EHEA) at 600 degrees C, 700 degrees C, 800 degrees C, 1000 degrees C and 1200 degrees C for 1 h, 2 h, 4 h, 10 h and 50 h are investigated. Under heat treatment at 600 degrees C, 700 degrees C and 800 degrees C, the FCC phase (CoCrFe phase) precipitates in the B2 phase, which improves the tensile strength (from 1007 MPa to 1173 MPa) and compression strength (from 1847 MPa to 2850 MPa), but declines the elongation (from 18.4% to 13.3%) and compression strain (from 43% to 39%). Meanwhile, the precipitate fraction increases with increasing tem-perature and the size of precipitated phase increases with increasing holding time at 600 degrees C, 700 degrees C and 800 degrees C. After holding at 1000 degrees C and 1200 degrees C, the FCC phase dissolves in the B2 phase, which softens the alloy. The elongation (from 18.4% to 20.3%) and compression strain (from 43% to 49%) increase and the alloy still remains good tensile and compression strength. This work indicates the mechanisms of heat treatment on the microstructure and mechanical properties of the alloy.(c) 2023 Published by Elsevier B.V.