Tensile deformation and fracture of Ti-5Al-5V-5Mo-3Cr-1.5Zr-0.5Fe alloy at room temperature

A combination of transmission electron microscopy, scanning electron microscopy and x-ray diffractometer is used to analyse the deformation mechanism and the fracture behavior of bi-model structure Ti-5Al-5V-5Mo-3Cr-1.5Zr-0.5Fe alloy during uniaxial tensile test. In the uniform deformation region, the strain of the primary α particles is dominated by the planar slipping and the dislocation tangling, and the deformation of the β matrix is accompanied by the dislocation tangling. In the necking region, the additional deformation twinning is found in the primary α particle, and the β phase is still strained by the dislocation tangling. The local shearing occurs in the necking region and results in the micro-twinning dominated deformation in secondary α precipitation and the 〈110〉_β fiber texture. The room temperature tensile fracture of Ti-55531 alloy is extremely sensitive to the formation of the voids, and the critical dimension of the crack is the diameter of the primary α particles.