Analysis of volume effects of phase transformation in titanium alloys

Some results of studies have been presented, concerning possibility of computer technology application in the prediction of transformation temperatures, lattice parameters and volume effects of transformations in two-phase titanium alloy heated at various rates. To do so, a methodology has been introduced, based upon a mathematical description of a physical model of a diffusional phase transformation. To estimate the changes of lattice parameters Vegard's rule have been applied that allows the phase lattice parameters to be determined out of its chemical composition. Furthermore, it has been assumed that the external volume effects of transformations are the resultant of changes of the alloy phase composition, the chemical composition of the component phases and their specific volummes. The calculated results have been experimentally verified in high temperature x-ray diffraction studies, dilatometric tests and microanalytical observations. Good agreement of the calculations with the experimental data has been proved.