β to ω phase transformation due to aging in a Ti–Mo alloy deformed in impact compression

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2003-06, Vol.350 (1), p.133-138
• Main Authors: Sukedai, E., Yoshimitsu, D., Matsumoto, H., Hashimoto, H., Kiritani, M.
• Format: Article
• Language: English
• Subjects: Aged ω-phase crystals; Applied sciences; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Electron microscopy; Equations of state, phase equilibria, and phase transitions; Exact sciences and technology; High-speed compressive deformation; Materials science; Metals. Metallurgy; Nucleation sites; Physics; Solid solution hardening, precipitation hardening, and dispersion hardening; aging; Solid solution, precipitation, and dispersion hardening; aging; Solid-solid transitions; Specific phase transitions; Ti–Mo alloy; Treatment of materials and its effects on microstructure and properties; Vacancy cluster
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/S0921-5093(02)00714-1

We investigated the roles of vacancies and their clusters introduced in a Ti–20mass% Mo alloy by high-speed compression in the formation of aged ω-phase crystals. Specimens were deformed by a static compression mode and a high-speed compression mode, and were then aged. The relationships between morphology of aged ω-phase crystals and deformation modes are discussed along with the roles of vacancies and their clusters in the nucleation and growth of aged ω-phase crystals. Aged ω-phase crystals were found to be smaller but of higher density in a high-speed deformation specimen. These results suggest that vacancies and their clusters easily become nucleation sites of aged ω-phase crystals. Several aged ω-phase crystals in a high-speed deformation specimen were of string-like shape. High-resolution electron microscopy confirmed that the string-like crystals have the ω-phase crystal structure. One of the roles of vacancies of and their clusters introduced by high-speed deformation is considered to be relief of compressive stress, which is predicted to arise in the course of transformation.