Thermodynamic calculation of the two-phase Ti alloy was completed using Compu Therm Pandat? and Ti data base, followed by isothermal compression of Ti6 Al4 V(Grade 5), with an initial colony lamellar structure that wa...Thermodynamic calculation of the two-phase Ti alloy was completed using Compu Therm Pandat? and Ti data base, followed by isothermal compression of Ti6 Al4 V(Grade 5), with an initial colony lamellar structure that was performed in the(α+β) and β-phase field. Microstructural evolution and phase transformation were investigated using X-ray diffraction, scanning and transmission electron microscopy. The presence of the Ti3 Al or α2(hcp), the phase stability and transition temperatures were predicted by the Gibbs free energy-temperature and phase fraction-temperature diagrams. The isothermal compression in the(α+β)-phase field is characterized by reorientation and localized kinking of α/β lamellae, and cracking at α/β interphase regions. While in the α→β-phase transformation area, deformation in β-phase and at α/β interphase boundaries, extensive transformation of α into β-phase, martensitic transformation and spheroidization of α-laths mainly characterize this isothermal compression. A complete transformation of α into β single phase occurs in the β-phase field. Ti3 Al or α2(hcp),β(bcc) and α(hcp)-phase, and additional hcp α’ and orthorhombic α' phases in a deformed Ti6 Al4 V are revealed. The flow stress level, the dynamic recovery and dynamic globularization are affected by deformation temperature.展开更多
基金The funding of this project by the South African Department of Science and Technology (DST)
文摘Thermodynamic calculation of the two-phase Ti alloy was completed using Compu Therm Pandat? and Ti data base, followed by isothermal compression of Ti6 Al4 V(Grade 5), with an initial colony lamellar structure that was performed in the(α+β) and β-phase field. Microstructural evolution and phase transformation were investigated using X-ray diffraction, scanning and transmission electron microscopy. The presence of the Ti3 Al or α2(hcp), the phase stability and transition temperatures were predicted by the Gibbs free energy-temperature and phase fraction-temperature diagrams. The isothermal compression in the(α+β)-phase field is characterized by reorientation and localized kinking of α/β lamellae, and cracking at α/β interphase regions. While in the α→β-phase transformation area, deformation in β-phase and at α/β interphase boundaries, extensive transformation of α into β-phase, martensitic transformation and spheroidization of α-laths mainly characterize this isothermal compression. A complete transformation of α into β single phase occurs in the β-phase field. Ti3 Al or α2(hcp),β(bcc) and α(hcp)-phase, and additional hcp α’ and orthorhombic α' phases in a deformed Ti6 Al4 V are revealed. The flow stress level, the dynamic recovery and dynamic globularization are affected by deformation temperature.
