Microstructure and mechanical properties of the (TiZrV)100-xAlx medium-entropy alloys

Abstract

High-strength and low-density materials are always needed in the aerospace, transportation, and other fields where lightweight is strictly required. The concept of the high-entropy alloy provides a new idea for designing the alloy with lightweight and high-strength. Mechanical properties and microstructure of the (TiZrV)100-xAlx (x = 10, 16, 25, at. %) medium-entropy alloys with different element Al content were investigated. With the increase of the element Al content in the (TiZrV)100-xAlx (x = 10, 16, 25, at. %) medium-entropy alloys, the densities of the specimens with the x = 10, 16, and 25 are 5.49, 5.37, and 5.15 g cm−3, respectively. The (TiZrV)90Al10 alloy and the (TiZrV)84Al16 alloy consist of the Ti(Zr,V) matrix phase and the ZrAl2 and Zr–V second phases, while the second phases in the (TiZrV)75Al25 alloy include the ZrAl2 and Zr–V and VAl2 phases. Also, more element Al is added, the coarser second phase grains tend to form in the alloys, resulting in decreasing of the room-temperature ductility and increasing of the high-temperature mechanical strength. Compressive ratio of the (TiZrV)100-xAlx (x = 10, 16, 25, at. %) medium-entropy alloys are larger than 30% at 1000 °C, and the (TiZrV)75Al25 alloy has a yield strength 184 MPa. The second phase grains are dispersed in the matrix, which can improve the deformation resistance of the alloy.