A study of intergranular fracture in nickel aluminide using the electron backscattering pattern method
Abstract
The electron backscattering pattern (EBSP) method has been used to study the distribution of grain boundaries that fracture at room temperature in Ni$\sb3$Al to statistically establish the effects of grain boundary geometry on crack propagation. Cracks were introduced by performing bending tests on Ni$\sb3$Al melt-spun ribbons which are one grain thick. The misorientations of cracked boundaries and boundaries at random positions were measured using the EBSP method and were then classified by $\Sigma$ values according to the coincidence site lattice (CSL) model. The distribution of boundary characters, classified by $\Sigma$ values, was compared for cracked boundaries and uncracked boundaries at random positions in the sample. Low angle boundaries and $\Sigma$3 boundaries, the majority of which are symmetrical boundaries, are found to resist crack propagation. All other boundaries appear to show an equal propensity for cracking. Specifically, there is no indication that low $\Sigma$ (except $\Sigma$3) boundaries as a group resist crack propagation. These results are compared to the predictions of recent theoretical models, specifically, the new dynamic micro-mechanic fracture model and the structural unit model, and generally good agreement is found.
Subject Area
Materials science
Recommended Citation
Lin, Hui, "A study of intergranular fracture in nickel aluminide using the electron backscattering pattern method" (1991). Dissertations available from ProQuest. AAI9125707.
https://repository.upenn.edu/dissertations/AAI9125707