Decomposition of the metastable beta phase in the all-beta alloy Ti-13V-11Cr-3Al

The phase transformations which occur in the all-β titanium alloy Ti-13V-llCr-3Al at temperatures below ∼ 500°C have been studied by transmission electron microscopy, X-ray diffraction, and electrical resistivity techniques. The decomposition of the metastable β phase has been found to proceed through a transition reaction leading to the formation of two bcc phases rather than through the precipitation of the ω phase as has been previously reported. An interpretation of the observed decomposition sequence, based on thermodynamic reasoning, is presented. The decomposition characteristics of the Ti-13V-llCr-3Al alloy have been compared with those of a Ti-13V-llCr alloy to determine the influence of aluminum on the transformation behavior.