Localized deformation at the grain boundary in Al-1%Mg₂Si base alloys

Tensile test was performed in order to clarify a part of localized deformation at the grain boundary in the intergranular fracture of age-hardened Al-1%Mg₂Si base alloys. The scratched marks on the surface were split into segments having gaps between them at the grain boundaries with increasing of deformation. The gaps had the maximum value at the mid point of grain boundary when the angle between the grain boundary and the tensile axis had 50-60 degrees deviation. This fact shows a possibility that an unusual deformation such as grain boundary sliding may be occured in this alloy. At some grain boundaries there were the steps that were formed by the vartical displacement between the neighboring grains at specimen surface. This phenomenon could not be interpreted by the conventional model of the grain boudary sliding.