Composition Design and Microstructure Optimization of a Metastable β‐Type Titanium Alloy with Ultrahigh Strength

A metastable β‐type Ti alloy, Ti‐7.46 V‐5Mo‐3.13Cr‐3Zr‐3Al (wt%), has been meticulously crafted utilizing the empirical composition design methodology, focusing on Mo equivalent equalization, bond order ( B o ), and metal d‐orbital energy level ( M d ) electronic parameters. Through a process involving homogenized alloy intermediate annealing during rolling and subsequent aging treatment, this alloy achieves a refined β‐phase matrix with finely dispersed α precipitation. Following annealing, electron backscatter diffraction reveals well‐defined β grains midway through the rolling process, with the average grain size of the annealed alloy measured as 17 μm. Subsequent scanning electron microscope and transmission electron microscope images exhibit numerous small and dispersed α phase precipitates within β grains postaging at 500 °C for 30 h. Computational analysis using JMatPro software indicates an average spacing of 0.033 μm between α phases, contributing to the alloy's exceptional yield strength. Upon aging, room temperature tensile tests demonstrate a remarkable yield strength of ≈1570 MPa with an elongation of 4%. The alloy's strength characteristics are further elucidated through the strengthening model and molecular dynamics model calculations, which closely align with experimental findings.