In-situ investigation of Kinetics of Phase Transformation of Ti54M Titanium Alloy by Electrical Resistivity

Abstract

The kinetics of phase transformation of Ti54M titanium alloy was investigated using electrical resistivity measurement for different heating cycles. The resulting microstructure parameters were analyzed using Aphelion software. It was found that α-phase starts to decompose to β-phase is between 600°C and 780°C. The temperature at which 100% β-phase was formed is 965°C. Beyond the temperature at which α-phase starts to decompose and despite the high heating rate of 10 °C/s, a rapid decrease of electrical resistivity which is attributed to dissolution of a-phase was observed. During isothermal holding, equilibrium was reached in about 15 minutes regardless of the holding temperature and differences in electrical resistivity observed at room temperature. A rapid increase in electrical resistivity during quenching which is attributed to martensitic transformation was observed and enhanced with increasing holding temperature. As expected, the fraction of α-phase, the surface density and average equivalent diameter of α-nodules decreased with increasing holding temperature. A good correlation between the variation of electrical resistivity and the fraction of a-phase obtained by image analysis after isothermal holding at different temperatures confirms that in-situ measurement of electrical resistivity can be used to determine the kinetics of phase transformation.