Microstructural characteristics and unique properties obtained by solution treating or aging in β-rich α+β titanium alloy

A β-rich α+β titanium alloy, SP-700 with Ti–4.5%Al–3%V–2%Mo–2%Fe exhibits unique properties in as-solution treated condition or upon subsequent aging. Stress-induced transformation and a high value of internal friction were caused by solution treating, and the age-hardening response in SP-700 was largely accelerated compared with other heat treatable titanium alloys. The relationship between these properties and nano-scale microstructure obtained by this heat treatment is discussed.