Tensile properties and fractographs of Ti–2.5Al–1.5Mn foils at different temperatures

The tensile properties and fractographs of Ti–2.5Al–1.5Mn foils at different temperatures were investigated. It is observed that material properties closely correlate with the thickness (T) to grain size (d) ratio and deformation temperature. Tensile analysis shows that local deformation is the main deformation feature in foils forming at room temperature, which may lead to premature fracture. The causes of inhomogeneous deformation behavior are the limited number of deformable grains contained in deformation zone and the weak transferability of hardening among different grains. Fracture analysis reveals that the size of dimples can represent the ductility of foils at room temperature. With the further increase of deformation temperature, the main plastic deformation mode of foils is transformed from intragranular dislocations and twin crystal to grain-boundary gliding and rolling. In conclusion, foil forming at elevated temperature can increase the hardening transferability and the number of deformable grains in deformation zone, which is an effective method to improve the formability and reduce the scatter of material properties.