Grain boundary engineering based on fractal analysis for control of segregation-induced intergranular brittle fracture in polycrystalline nickel |
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| Authors: | S Kobayashi T Maruyama S Tsurekawa T Watanabe |
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| Affiliation: | 1. Division of Mechanical and Electrical Engineering, Department of Innovative Engineering, Faculty of Engineering, Ashikaga Institute of Technology, Omae-cho 268-1, Ashikaga, Tochigi 326-8558, Japan;2. Department of Materials Science and Engineering, Graduate School of Science and Technology, Kumamoto University, Kumamoto 860-8555, Japan;3. Key Laboratory for Anisotropy and Texture of Materials, Northeastern University, Shenyang 110004, China |
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| Abstract: | 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-Σ coincidence site lattice (CSL) boundaries shows higher fracture resistance than the specimen with coarse-grained structure and a lower fraction of low-Σ 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-Σ 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. |
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