Abstract:Compressive mechanical behavior and microstructure evolution of Ti-5.7Al-2.9Nb-1.8Fe-1.6Mo- 1.5V-1Zr alloy under extreme conditions were systematically investigated. The results show that strain rate and temperature have a significant influence on the mechanical behavior and microstructure. The alloy exhibits a positive strain rate sensitivity and negative temperature sensitivity under all temperature and strain rate conditions. The hot- rolled alloy is composed of a bimodal structure including an equiaxed primary α_p phase and a transformed β phase. After compression deformation, the bimodal deformed structural features highly rely on the temperature and strain rate. At low temperature and room temperature, the volume fraction and size of α_p phase decrease with increasing temperature and strain rate. At high temperature, the volume fraction of the α phase is inversely correlated with temperature. A modified Johnson-Cook constitutive model is established, and the predicted results coincide well with the experimental results.

Key words: titanium alloy; extreme condition; mechanical behavior; microstructure; modified Johnson-Cook constitutive model