Superior creep resistance of multiscale architectural titanium matrix composites: Insights from microscale internal stress

The higher the internal stress, the lower the effective stress. Increasing the internal resistance to dislocation motion is essential for improving the creep resistance of metallic materials. By introducing hybrid reinforcements and regulating their distributions, the multiscale architectural (TiB+(Ti,Zr)₅Si₃)/Ti55 composites exhibited superior creep resistance at 650 °C, with a rupture life of ∼189 h under 200 MPa. Utilizing stress-reduction and stress-compensation creep tests, the internal stress within the composites was proven to be ∼30 MPa higher than that within the alloys. Microstructural characterizations revealed that the enhanced internal stress originated from the modulus strengthening of reinforcements and the dislocation pile-up strengthening of substructures. Our findings provide a new perspective for understanding the improved creep resistance caused by compositing.