Hot Rolling on Microstructure and Properties of NbHfTiVC_0.1 Refractory High-Entropy Alloy

NbHfTiVC0.1 refractory high-entropy alloy (RHEA) exhibits excellent comprehensive mechanical properties and demonstrates great potential for applications. However, the mechanical properties need to be improved further. In this work, hot rolling on NbHfTiVC0.1 RHEA at temperatures of 650 degrees C, 850 degrees C, and 1050 degrees C, with total reductions of up to 30%, 50%, 70%, and 80%, was conducted. The microstructure and mechanical property evolution of the samples were further investigated. The hot-rolled samples at 650 degrees C and 850 degrees C exhibit a composition consisting of BCC, carbide, and Laves phases, whereas the samples rolled at 1050 degrees C only consist of BCC and carbide phases. The 650-80 sample displays the highest ultimate tensile strength (1354 MPa), and the 1050-80 sample demonstrates the highest elongation (16%). The highest strength observed in the 650 degrees C-80% sample can be attributed to the presence of fractured and refined carbides, fine-grains, and the hindrance of dislocation slip by the fine Laves phase. At a higher rolling temperature (1050 degrees C), the Laves phase disappears, resulting in a reduction in strength but an increase in plasticity. Furthermore, the dislocation slipping mechanism within the BCC matrix also contributes positively to plastic deformation, leading to a notable increase in ductility for the 1050 degrees C-80% sample. These research findings provide valuable insights into enhancing the strength and ductility simultaneously of NbHfTiVC0.1 RHEA through hot rolling.