Fatigue Crack Growth of Silicon Nitride at 1400°C: A Novel Fatigue-Induced Crack-Tip Bridging Phenomenon |
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Authors: | Shih-Yu Liu I-Wei Chen Tseng-Ying Tien |
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Affiliation: | Department of Materials Science and Engineering The University of Michigan, Ann Arbor, Michigan 48109-2136M |
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Abstract: | high-strength Si3N4with elongated β-Si3N4 and equiaxed α-sialon was tested in cyclic and static fatigue at 1400°C. At low stress intensity factors and high frequencies, the pullout process of the elongated grains was enhanced, which suppressed the crack growth. This provides a possible explanation for the increased lifetime under cyclic leading conditions reported for ceramics by several investigators. While crack-healing by high-temperature annealing was found to greatly reduce the subsequent static fatigue crack growth rate, it had only a modest effecf on cyclic fatigue and none at high frequencies. |
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