Migration behaviors of boundaries in polycrystalline metals during grain growth process

Abstract

New equations for grain growth process induced by migration of boundary ligaments and corners were deduced, in order to overcome the shortcoming of the conventional basic theory for normal grain growth in three dimensional polycrystals. The Kelvin's 14-sided polyhedron was assumed as basic shape of the grains. The evolutions of ligament density and corner density during grain growth as well as their influences on grain growth rate and migration activation enthalpy were analyzed. The grain growth process of an experimental Fe-3%Si alloy was simulated based on the new equations. It was indicated that the boundary migration driven by motion of ligaments and corners, especially the latter one, comes closer to the real grain growth process, and the shortcoming in conventional equation has been modified obviously. The evolution tendency of activation enthalpy for boundary migration calculated agrees with the actual observations. The new equations did not yet include the effects of second phase particles and solute atoms in three dimensional polycrystalline metals, and therefore could not describe the real process perfectly, which needs to be improved further.