Phase Evolution of Novel MoNbSiTiW Refractory High-Entropy Alloy Prepared by Mechanical Alloying

Abstract

Refractory high-entropy alloys (RHEAs) are new types of material that have been developed for high-temperature applications. RHEAs should have enhanced high-temperature strength while maintaining a sufficient level of room-temperature toughness. The phase evolution of novel MoNbSiTiW RHEAs was investigated after mechanical alloying (MA) for 35 h. X-ray diffraction (XRD) was used to analyze the phase evolution, and analysis of particle morphologies was done using a scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS). XRD results indicate that NbMoSiTiW RHEAs with up to 10 h of mechanical alloying have a stable solid solution phase with body centered cubic (BCC) structure. Further milling of NbMoSiTiW RHEAs promotes the evolution of intermetallic compounds until 35 h of mechanical alloying. The Williamson-Hall process was incorporated for crystalline size and lattice strain measurement and the results show that, after 35 h of mechanical alloying, the crystalline size decreased from 298 nm to 25 nm, and an enhancement in lattice strain was observed from 0.1% to 0.65%.