A criterion for grain-size limit of polycrystalline materials

Abstract

The transformation from the crystalline to the amorphous state was frequently found in some polycrystalline materials when grain refinement reaches a certain degree. Grain-size reduction induced lattice distortion and its effects on crystal structural instability were analyzed based on our recent work [Qin, Philos. Mag. Lett. 88, 169 (2008); Qin, J. Appl. Phys. 102, 124303 (2007); Qin, J. Phys.: Condens. Matter 19, 236217 (2007)] and Koike's model [Phys. Rev. B 47, 7700 (1993)]. A criterion for determining the possible grain-size limit below which the amorphization occurs was proposed. Theoretical results may well account for experimental observations. © 2009 American Institute of Physics.