1 National Innovation Institute of Defense Technology, Academy of Military Sciences, Beijing 100071, China 2 School of Materials Science and Physics, China University of Mining and Technology, Xuzhou 221116, Jiangsu, China
Refractory high entropy alloys NbMoTaWTi and NbMoTaWZr were prepared by vacuum arc melting.The microstructure and component distribution characteristics were analyzed, and the dynamic behavior during room temperature to 1500℃, as well as the isothermal oxidation behavior at 1200℃ were studied. Results reveal that NbMoTaWTi mainly consists of single body-centred cubic (BCC) phase, and NbMoTaWZr is composed of BCC and Zr-rich phases.These two alloys are both seriously oxidized above 700℃. Comparatively, NbMoTaWTi alloy is superior to NbMoTaWZr in antioxidation below 1300℃.For both two alloys, the oxygen diffusion inward mainly occurs during isothermal oxidation at 1200℃ and catastrophic oxidation takes place after 3 h. The Ti and Zr addition cannot cause selective oxidation. Although these two elements form a composite oxide layer with other refractory metal oxides, the density and the ability to prevent oxidation is not enough.
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