Microstructure and strengthening mechanisms of novel lightweight TiAlV0.5CrMo refractory high-entropy alloy fabricated by mechanical alloying and spark plasma sintering

Lightweight TiAlV0.5CrMo refractory high-entropy alloy (RHEA) with ultra-fine grains was initially fabri-cated by mechanical alloying (MA) and subsequent spark plasma sintering (SPS). The microstructural evolution, mechanical performance and strengthening mechanisms of the alloys in various processing conditions were systematically characterized. A single body-centered cubic (BCC) solid solution phase with nanocrystalline structure was formed after milling for 30 h. Afterward, the BCC2 and Al2O3 phases were precipitated from the supersaturated BCC structure during the sintering process in the temperature range from 1100 to 1300 degrees C. The specimen with an average grain size of-0.47 mu m and an precipitation phase of less than-0.15 mu m was obtained at sintering temperature of 1200 degrees C, exhibiting ultra-high micro-hardness of 10.26 GPa, acceptable compressive yield strength of 1825 MPa, outstanding ultimate compressive strength of 2989 MPa and satisfactory plastic strain of 17.8% at room temperature. The excellent mechanical properties of the TiAlV0.5CrMo RHEA were dominantly attributed to the combined effects of inherent solid solution strengthening, grain boundary strengthening and precipitation strengthening. It is anticipant that the process of combining MA and SPS is the effective method to produce novel lightweight and refractory structural material with outstanding performance.(c) 2022 Elsevier B.V. All rights reserved.