Fracture Strength of Grain Boundaries in Ni3Al

Abstract

ABSTRACTThe fracture strength of grain boundaries in Ni3Al was quantitatively measured by performing tensile tests on miniature bicrystal specimens with various grain boundary types. A fairly good relationship between fracture mode, fracture strength and Σ value was established. The Σ1, Σ3 and Σ9 boundaries were found to be strongly crack-resistant but the adjacent bulk fractured. In contrast, Σ5, Σ7, Σ11, Σ13 and random boundaries were found to be less crack-resistant and fractured at lower stresses than the fracture strength of the bulk. In the latter case, the fracture strength of the Σ11 and Σ13 boundaries was higher than that of the Σ5 and Σ7 boundaries. Most random boundaries were as weak as the Σ5 and Σ7 boundaries, but some exhibited high fracture strength comparable to that of the Σ11 and Σ13 boundaries.