Effects of Grain Boundaries on the Tensile Deformation of Non-Isoaxial Bicrystals of Aluminium

Abstract

Non-isoaxial bicrystals and their component single crystals of 99.99 wt% aluminium were investigated by the tensile test. The yield stress (ε=0.2%) and the hardening rate in the easy glide region were examined in reference to the misorientation and Young’s modulus between the component crystals.
In about one-half of the specimens, the yield stress of the bicrystals was smaller than that of the component single crystals. It is shown that the grain boundary of the non-isoaxial bicrystal may promote the deformation in a certain condition, where the misorientation between the preferred slip systems of two component crystals in the vicinity of the grain boundary was small. The difference in Young’s modulus between the two component crystals was not a major factor for lowering the yield stress of the bicrystals below those of the two component single crystals.
It was observed that the slip systems having the highest Schmid’s factor were not always preferred in the vicinity of the grain boundary, but those having Schmid’s factor above 0.40 and small misorientation were preferred.