Recent Advances in the Design of Novel β-Titanium Alloys Using Integrated Theory, Computer Simulation, and Advanced Characterization

Metastable β-titanium (β-Ti) alloys, because of their combination of high specific strength, superior corrosion resistance, and excellent biocompatibility, have found increasingly widespread application in aerospace, automobile, biomedical, and chemical industries. Many different pathways, available for phase transformation and deformation between a high-temperature β and a low-temperature α phase, provide ample opportunities to engineer the desired microstructure through thermal mechanical processing for optimal properties targeting specific applications. Based on an integrated approach (theory, crystallography, multiscale modeling, and advanced characterization), recent studies have obtained fundamental insights in both designing strategies by exploring a variety of nonconventional solid-state phase transformation and deformation pathways, including 1) pseudospinodal decomposition; 2) precursory ω-phase-assisted α precipitation with a wide range of tunable size scales and number densities; and 3) abnormal high-index deformation twinning modes. Herein, the revolutionary new concepts for alloy development and deployment and the underlying physical mechanisms are reviewed in detail. Perspectives on the future research directions in the development of metastable β-Ti alloys are also offered. The mechanisms and alloy design concepts as well as the advantage of using state-of-the-art computational and characterization tools in a correlative manner for alloy design are applicable to a wide range of metallic materials beyond Ti alloys.