材料期刊网

The dynamic globularization kinetics of Ti-6.5Al-1.5Zr-3.5Mo-0.3Si alloy with a colony alpha microstructure during deformation at temperature range of 920-980 degrees C and strain rate range of 0.01-10 s(-1) was quantitatively characterized and investigated. The results show that both the globularization fraction and globularized grain size were sensitive to deformation conditions. At temperature higher than 950 degrees C, strain rates higher than 0.1 s(-1) and true strain around 3, enhanced grain refinement was achieved through dynamic globularization. The refined structure shows improved superplasticity characteristics including near fully equaxied alpha grains around 1 mu m, discontinues beta phase and high dislocation density at the globularized grain boundaries. The dynamic globularization kinetics characteristic was associated with deformation mechanism that controls the dynamic globularization process. (C) 2009 Elsevier B.V. All rights reserved.