Local softening deformation and phase transformation induced by electric current in electrically-assisted micro-compression of Ti-6Al-4V alloy

Electric current induced local softening behaviors were investigated using electrically-assisted micro -compression (EAMC) tests of Ti-6Al-4V alloy in this study. It was found that the flow curves showed a S-shape characteristic at higher current density and larger strain rate, i.e. the local softening dominated by the uneven distribution of Joule heat temperature. Numerical simulations were adopted to analyze the Joule heat temperature and the strain filed distributions in different deformation zones during EAMC. The time functions of the instantaneous strain in the center of softening deformation regions were calculated to contrast the differences between the EAMC and the uniform deformation. It turned out that the plastic strain at the center of the sample was accelerated compared to the rest of the test section during EAMC. Based on the microstructural observations, a alpha-*beta-*alpha MODIFIER LETTER PRIME phase transformation mode was put forward to illustrate the electric current induced phase transformation, in which the hotspots effect of local Joule heat was a main driving for the nucleation of new beta phase at a relatively low temperature. The proposed local softening deformation method induced by electric current in the fabrication of micro-parts for titanium alloy is possible due to the high heating efficiency for material and controllable temperature field for billet.

Automated summary

Electric current induced local softening behaviors of Ti-6Al-4V alloy were investigated using electrically-assisted micro-compression tests in this study. It was found that at higher current density and larger strain rate, there was local softening dominated by uneven distribution of Joule heat temperature.