PHASE-TRANSFORMATIONS IN TI-3AL-8V-6CR-4ZR-4MO

The time-temperature-transformation behavior of a metastable β-titanium alloy, Ti-3A1-8V-6Cr-4Zr-4Mo (RMI 38644), has been examined using hardness, X-ray measurements, and optical and transmission electron microscopy. This examination has shown that a variety of metastable and stable phases may form in this alloy system. These include metastable zones, ω, both Burgers (Type 1) α and non-Burgers (Type 2) α, TiCr2, and a Ti-Zr-silicide. A composite TTT diagram is presented which describes the influence of aging time and temperature on the stability of these phases. Finally, the appearance of these transformation products is correlated with the observed hardness changes when RMI 38644 is aged at elevated temperatures. © 1979 American Society for Metals and the Metallurgical Society of AIME.