Weak grain boundaries in Ni3Al

This study correlates the resistance to intergranular crack initiation with grain boundary character in Ni3Al by comparing the distribution of grain boundary characters at crack initiation sites to that in the general population. Micro-cracks were initiated in Ni3Al by tensile deformation of Ni3Al ribbon/brass bar samples in a pressurized chamber, and the boundary characters were determined using the electron backscattering pattern (EBSP) method. It has been found that low-angle and Σ3 boundaries are strong, and are resistant to crack initiation; all high-angle boundaries, including low-Σ (5 < Σ < 29) boundaries, are similarly prone to crack initiation, and Σ15, Σ21, and Σ29 boundaries are probably some of the weak boundaries in Ni3Al.