Microstructural evolution and mechanical behavior of novel Ti1.6ZrNbAl lightweight refractory high-entropy alloys containing BCC/B2 phases

To demonstrate the concept of lightweight refractory high-entropy alloys (LRHEAs) with remarkable strength and ductility at room- and high temperatures, we designed and fabricated novel Ti1.6ZrNbAlx (x = 0.3, 0.4, 0.5 and 0.65) LRHEAs with a relatively low density (<∼5.9 g/cm3). The presence of B2 coherent precipitates and their interactions with moving dislocations is proposed to be responsible for the measured high tensile yield strength (>800 MPa) and satisfactory tensile ductility (>10%) at room-temperature. The compressive peak stress exceeding 500 MPa at 600 °C supports the potential application of these LRHEAs as high-temperature structural materials. Our work provides a framework that can be used to guide the design of high-performance LRHEAs for high-temperature applications.