Grain boundary engineering based on fractal analysis for control of segregation-induced intergranular brittle fracture in polycrystalline nickel

作者：Kobayashi S^*; Maruyama T; Tsurekawa S; Watanabe T

来源：Acta Materialia, 2012, 60(17): 6200-6212.

DOI：10.1016/j.actamat.2012.07.065

• Segregation-induced fracture
• Grain boundary character distribution
• Random boundary connectivity
• Grain boundary engineering
• Fractal analysis

The effect of grain boundary microstructure on the fracture resistance of sulfur-doped polycrystalline nickel was investigated using specimens with different grain boundary microstructures to reveal the usefulness of grain boundary engineering for control of segregation-induced intergranular brittle fracture of polycrystalline materials. The sulfur-doped polycrystalline nickel specimen with more homogeneous fine-grained structure and a higher fraction of low-Sigma coincidence site lattice (CSL) boundaries shows higher fracture resistance than the specimen with coarse-grained structure and a lower fraction of low-Sigma CSL boundaries. It was found that high-energy random boundaries play a key role as the preferential crack path in fracture processes. The resistance to sulfur segregation-induced intergranular brittle fracture was evaluated by analyzing the fractal dimension of random boundary connectivity in the polycrystalline nickel specimens studied. The fractal dimension of random boundary connectivity decreases with increasing fraction of low-Sigma CSL boundaries, resulting in the generation of a higher fracture resistance by restricting more frequent branching and deflection of propagating crack path along random boundaries from the main crack.

• 出版日期2012-10
• 单位东北大学