Microstructure and Mechanical Properties of Novel Lightweight TaNbVTi-Based Refractory High Entropy Alloys

A series of novel lightweight TaNbVTi-based refractory high entropy alloys (RHEA) were fabricated through ball-milling and spark plasma sintering (SPS). The reinforced phase of TiO precipitates were in-situ formed due to the introduction of Al2O3 ceramic particles. The RHEA with 15% Al2O3 exhibits a high compressive yield strength (1837 MPa) and a low density (7.75 g/cm(3)) with an adequate ductility retention. The yield strength and density are 32% higher and 15% lower, respectively, compared to the RHEA without Al2O3 addition. The specific yield strength (237 MPa cm(3)/g) of the RHEAs is much higher than that of other reported RHEAs, and is mainly ascribed to the introduction of high volume fraction of Al2O3 additives, resulting in solid solution strengthening and precipitation strengthening. Meanwhile, the ductile matrix is responsible for the good compressive plasticity.