Achieving an effective increase in wear resistance over a wide temperature range for Ti₅₀Zr₃₀Nb₁₀Al₁₀ refractory multi-principal element alloy: The introduction of a robust and deformable α2 phase

The limited wear resistance of multi-principal element alloys (RMPEAs) over a wide temperature range seriously restricts its further development and application. Though introducing a hard phase into the RMPEAs matrix is considered to be a common strategy to relief this contradiction, the brittleness of the hard phase and resulting heterogeneous interfaces often lead to unstable failure under prolonged wear conditions. In this work, a strong and deformable (Ti,Zr)₃Al-type α2 phase was formed into Ti₅₀Zr₃₀Nb₁₀Al₁₀ RMPEAs through hot pressing and aging treatments to achieve robust wear performance over a wide temperature range, resulting in decreased wear rates and coefficient of friction of ∼50 % and ∼20 %, respectively. Based on the action of alternating frictional stress, multiple slip systems in the α2 phase are activated at room temperature. The good load-bearing and deformation capabilities of α2 phase are maintained up to 600 °C, thereby providing decreased wear rates form 17.3 × 10⁻⁴ mm³/Nm to 9.2 × 10⁻⁴ mm³/Nm. At higher temperatures (900 °C), the optimized alloy achieves the lowest wear rate of 0.6 × 10⁻⁴ mm³/Nm, which can be attributed to the Hall-Petch strengthening effect introduced by hot pressing and the protection of a dense oxide layer. These observations provide valuable insights for the design of superior wear-resistant RMPAs.