Unveiling the correlation between anomalous hardening and grain boundary diffusional transformation in ω single-phase nano-grained Ti-Fe alloy

A metastable ω single-phase nanograined (NG) Ti-Fe alloy was synthesized using laser inert-gas condensation (IGC). Upon being annealed at 360°C, the NG Ti-Fe alloy exhibited a remarkable ultra-hardening, increasing the hardness from 4.7 to 8.6 GPa. Subsequent findings revealed an unexpected hardness enhancement, rising from 6.6 GPa at 420°C to 7.6 GPa at 460°C, despite the occurrence of grain growth. In-depth investigations into the strengthening mechanisms of the NG Ti-Fe alloy were conducted using in-situ synchrotron high-energy X-ray diffraction (XRD) and transmission electron microscopy (TEM). The comprehensive analysis unveiled that the diffusion-controlled structure evolution during annealing played a pivotal role in enhancing the alloy's mechanical properties. This study not only presents the synthesis of a novel metastable alloy but also provides valuable insights into the intricate relationship between diffusion-controlled structure evolution and the resulting superior mechanical properties.