Design and characterization of Co-free Ni₂AlTi-based high-entropy alloys with excellent mechanical properties

Co-free high entropy alloys (HEAs) are highly valued for their exceptional castability and mechanical properties, making them suitable for high-temperature applications. In this study, we designed, successfully prepared, and characterized a novel alloy, (Ni₂AlTi)₅₀A₅₀, where A = FeCr, FeV, CrV. All three alloys exhibit intermetallic (L2₁) and body-centered cubic (BCC) phases. The Ni₂AlTiCrV and Ni₂AlTiFeCr alloys demonstrate excellent mechanical properties. Notably, the Ni₂AlTiCrV alloy has a remarkable yield strength of 1562 ± 168 MPa and a plasticity of 20.20 ± 2.73 %. The outstanding mechanical properties of Ni₂AlTiCrV can be attributed to its eutectic-like microstructure, which combines the order L2₁ phase with a ductile BCC phase. Additionally, the Ni₂AlTiCrV alloy exhibits a high hardness of 554 HV, a result of solid solution strengthening due to the addition of Cr and V. These excellent mechanical properties suggest that this HEAs system has great potential for application in high temperature fields.