Strain glass transition in a metastable β Ti-Nb-O alloy with high oxygen content

Abstract

Metastable β titanium alloys with the incorporation of multiple β-stabilizing elements could exhibit unique mechanical and functional properties. In the present study, a Ti-Nb-O metastable β titanium alloy with a high oxygen content of 5.2 at.% was prepared, and the microstructural evolution and dynamic mechanical behavior were systematically characterized. It was found that strain glass transition occurs in the Ti-Nb-O alloy, which is responsible for the invariant elastic modulus over a wide temperature range. The interstitial oxygen atoms dissolved in the Ti-Nb-O alloy suppress β-α′′ long-range martensitic transformation during cooling, which softens the elastic modulus of the alloy, while promote strain glass transition characterized by the formation of nano-domains, which hardens the elastic modulus. As the temperature decreases, the modulus softening of β matrix compensates for the modulus hardening caused by nano-domains due to anharmonic atomic vibration, thus giving rise to the temperature-independent elastic modulus, i.e. Elinvar effect.