Microstructure and Mechanical Properties of Unbtihf1-Xmox High-Entropy Alloys

In this study, the microstructure evolution, phase transition, and mechanical properties of UNbTiHf1-xMox (x = 0, 0.1, 0.3, 0.5, 0.7, 0.9, and 1) high-entropy alloys (HEAs) were investigated. The crystalline structure of the alloys changed from the initial single body-centered cubic (BCC) structure to a dual BCC structure. Thermodynamic analysis revealed that lattice distortion plays a great role in stabilizing the dual-phase microstructure over a single-phase one in the UNbTiHf1-xMox (x > 0.5) HEAs. The structural changes were accompanied by corresponding variations in compressive properties. The alloys with a single-phase BCC structure exhibited relatively low strength but extended plasticity, whereas those with a dual-phase BCC structure became extremely brittle. The calculated stress–stain relationships of the dual-phase alloys indicate that the microdeformation state of the alloys changed constantly and that stress–strain coordination behaviors are manifested between the constituent phases.