粒界拡散クリープ下における多結晶体中のキャビティの成長とき裂への遷移

概要

論文の詳細を見る
The stress distribution along grain boundaries of polycrystalline materials ahead of a cavity under Coble creep (grain boundary creep) condition is numerically analyzed in order to elucidate the effect of the grain boundary network on cavity growth. The stress gradient at the cavity tip, which is proportional to the changing rate in the cavity volume, points out that the grain boundary triple points interfere with the cavity growth, though the cavity grows faster beyond them. The deceleration effect due to the triple points diminishes as the cavity becomes larger. The transition from "crack-like cavity" to "crack" is also discussed on the basis of the stress distribution. "Crack-like cavity" and "crack" are distinguished by the fact that the latter possesses stress singularity in the vicinity of the tip while the former does not. The calculation reveals that the transition under the Coble creep condition does not take place before the cavity length exceeds 15 grain boundaries. The transgranular deformation due to dislocation creep drastically accelerates the transition.
1994-04-25