Effect of Sc and Y addition on the microstructure and properties of HCP-structured high-entropy alloys

This study aimed to design and prepare the following four kinds of refractory high-entropy alloys (RHEAs): TiZrHf, TiZrHfSc, TiZrHfY, and TiZrHfScY. All the four RHEAs showed a hexagonal close-packed (HCP)-based structure. Both the strength and ductility increased in the TiZrHfSc alloy compared with the TiZrHf alloy because of the addition of Sc element and the formation of a fine needle-like lamellar structure in the former. The mechanical properties of TiZrHfY and TiZrHfScY alloys decreased after the addition of Y element because of the segregation. The conductivity of TiZrHf, TiZrHfSc, TiZrHfY, and TiZrHfScY alloys decreased compared with that of pure Ti, Zr, Hf, Sc, and Y elements. However, their resistivity was comparable to the traditional electrical resistivity of the alloys at room temperature because of the serious lattice distortion in the HEAs. All the four alloys showed a typical paramagnetic behavior. These characteristics make the alloys suitable for industrial applications.