y Microstructures and mechanical properties of HfNbTaTiZrW and HfNbTaTiZrMoW refractory high-entropy alloys

W and Mo are added to the HfNbTaTiZr high entropy alloy to improve its high-temperature performance. Microstructures, and mechanical properties of new refractory high-entropy alloys, HfNbTaTiZrW (H-W) and HfNbTaTiZrMoW (H-MoW), were studied. W and/or Mo additions broaden the two-phases temperature range and introduced two disordered BCC phases in contrast with the single BCC phase in HfNbTaTiZr. Attributing to the dual-phases microstructure and the strong solid solution strengthening effect, H-W and H-MoW exhibit substantially improved yield strengths at 25-1200 degrees C compared with HfNbTaTiZr. Particularly, at 1200 degrees C, H-W and H-MoW show yield strengths of 345 MPa and 703 MPa, which are much higher than 92 MPa of HfNbTaTiZr. No phase change happens during compressive tests at high temperatures, indicating good phase stabilities of H-W and H-MoW alloys. (C) 2019 Elsevier B.V. All rights reserved.