The thermodynamics and kinetics of the β → αm transformation in three Ti-X systems

摘要: Abstract Continuous cooling experiments were used to study the β → α m transformation in three titanium base eutectoid systems: Ti-Ag, Ti-Au and Ti-Si. Using thermal arrest temperature vs rate data, T 0 enthalpy of transformation. ΔH , determined for eight alloys these sytems. Subsequent microstructural analysis yielded growth rates as a function reaction from which an estimation activation trans-interphase boundary diffusion, D b was made. The phase boundaries region each system re-evaluated found agree well with some previous investigations differ markedly others. Values range −2470 ± 500 −3270 460 J / mol (−590 120 −790 110 cal ). Most temperatures that bisector ( + ) region. vary 50 93 kJ/mol (11.7–22.2 kcal/mol). distance one second is calculated be ca. 6 × 10 −5 at 7 K undercooling compared equilibrium precipitate (when volume diffusion-controlled) 1 −7 same time temperature. These results further confirm identification massive investigated.