COMPATIBILITY STRESSES IN FATIGUED BICRYSTALS - DEPENDENCE ON MISORIENTATION AND SMALL PLASTIC-DEFORMATIONS

Compatibility stresses are calculated for twist boundaries about [(1) over bar 49] and a ''random'' high angle boundary between a [(1) over bar 49] grain and a [100] grain, assuming piecewise homogeneous elasti c fields and copper as model material. The ''in-plane'' compatibility stresses produced by uniaxial tension perpendicular to the boundary ar e a strong function of the crystallography of the grains and their mis orientation. The effects of small plastic strains via crystallographic slip are also studied for three particular misorientations ([(1) over bar 49] 90 degrees and 180 degrees twist boundaries and the ''random' ' misorientation) and the type and amount of slip close to the boundar y predicted by minimizing the elastic energy and using experimental me asurements of the axial component of the plastic strain. The predictio ns agree guile well with experimental observations of slip traces clos e to the boundaries of copper bicrystals with those misorientations te sted under high cycle fatigue conditions. (C) 1997 Acta Metallurgica I nc.