Heat-Treatment-Induced Dendritic Structure and Phase Evolution in a Cast AlCrFeMnNiW0.1 High-Entropy Alloy

Cast body-centred-cubic (BCC) high-entropy alloys (HEAs) such as AlCrFeMnNiW0.1 offer solid-solution strengthening and thermal stability; however, the response of cast alloys to post-solidification heat treatment across a broad temperature range remains insufficiently reported. Here, we investigated the cast HEA in the as-cast condition and after heat treatment at 800, 1000, and 1200 °C using SEM and XRD. EDS mapping at 1200 °C and an existing CALPHAD equilibrium calculation for the as-cast condition provided complementary evidence. The as-cast alloy exhibited a dendritic/interdendritic morphology and a diffraction pattern dominated by a reflection set consistent with a BCC lattice based on interplanar-spacing ratios. Heat treatment promoted microstructural refinement and progressive compositional homogenization, while the dendritic structure remained evident at 800–1200 °C. EDS mapping indicated comparatively higher elemental heterogeneity for W and Ni among the six mapped elements at 1200 °C. Vickers hardness decreased from 490 HV in the as-cast state to 371 HV at 800 °C, followed by recovery to 398 and 418 HV at 1000 and 1200 °C, respectively.