Electrothermal Stretching Behavior and Structure Evolution of Ti₂AlNb

With the pulse current of 50 A, 53 A, 57 A and 60 A, the equilibrium initial temperature of 700 ℃, 800 ℃,900 ℃ and 1000 ℃ was obtained respectively. With different strain rates, the electrothermal stretching test of Ti₂AlNb was carried out. By comparing, the mechanical properties and microstructure of Ti₂AlNb under the original state and different current states were analyzed. The results show that the mechanical properties of Ti₂AlNb gradually decrease with the increase of current and the decrease of strain rate. When the initial current is 50 A, 53 A and 57 A, the fracture mode of the sample is plastic fracture, showing microporous aggregation type. The failure mode under other loading current（initial temperature） and strain rate is fusing. As the loading current（initial temperature） increases, the O phase and α₂ phase decrease sharply. The α₂ phase decrease makes the binding effect on B₂/β phase weaken, and the B₂/β phase continuously grows. The decrease of strain rate is also associated with the decrease of O phase and α₂ phase content and the increase of B₂/β phase, which is essentially due to the effect of temperature.