The role of stress on initial stages of crystal growth

Abstract Crystallization in undercooled melts is accompanied by development of stress energy, due to the difference in volume of the new system as compared to the ambient phase. Therefore, the growth rate decreases with time. Here, the non-stationary differential equation is solved, accounting for the production of energy of stress deformation as well as for its reduction caused by relaxation. In this way the growth rate and the dependence of crystal size on time are obtained. The change of the growth rate is significant when new formed phase has composition different from the ambient phase, so that particles, creating the new phase can move much faster the main molecules of the matrix. A steady state is determined by the condition that the rate of stress energy production is equal the rate of stress energy consumption. The degree to which the stationary growth rate U st is reduced as compared to the initial growth rate U max is controlled mainly by the ratio of the self-diffusion coefficient of the building units to the diffusion coefficient of the building units creating the new phase. A clear break in the size versus time dependence of the growing crystal is seen.