Computer simulation and experimental investigation of the spinodal decomposition in the βTi-Cr binary alloy system

The spinodal decomposition of the beta Ti-Cr binary alloys system is still questionable, because there are only rare experimental and thermodynamics data; moreover, simulation results for a real alloy system have not been found. Transmission electron microscopy (TEM) and quantitative computer simulations based on Khachaturyan's diffusion equation have been employed to study the microstructural evolution occurring in the metastable beta Ti-Cr alloys. Our study results reveal that the metastable beta Ti-Cr undergoes a phase separation reaction beta --> titanium rich (beta(1)) + chromium rich (beta(2)) through a spinodal decomposition. The coherent two-phase fields show extremely fine platelike precipitates distributed homogenously through the bcc matrix, which are parallel to the {100} plane. Those precipitates are highly elastic induced from the first step of the phase separation. There is good agreement between the observed microstructure and the simulation results. The mode of formation of alpha phase is also discussed.