Kinetics of Crack-Induced Hydride Formation in Hexagonal Close-Packed Materials

The formation of a second phase, such as a brittle hydride, in presence of a crack is modeled for hexagonal close-packed metals. To this end, the Ginzburg-Landau phase-field formulation which relies on a sixth-order Landau potential is adopted. The crack-induced stress is implicitly included in the phase-field equation through the mechanical energy so only a single equation is solved providing computational efficiency. The second-phase precipitation evolution is studied for different crack inclinations in titanium and zirconium by using the finite volume method. The crack-induced stresses may lead to the phase transition temperature increasing above the system temperature in the crack-tip proximity. The resulting quenching effect induces a second-phase nucleation. The temporal evolution reveals that the transformation eventually reaches a steady state and the resulting precipitate geometry is dependent of the material parameters and conditions.