Point Defect Hardening in MgO·3Al2O3 |
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| Authors: | Hisayuki Suematsu Takayoshi Iseki Toyohiko Yano Yasutoshi Saito Tetsuya Suzuki Tsutomu Mori |
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| Affiliation: | Department of Inorganic Materials, Tokyo Institute of Technology, Tokyo 152, Japan;Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, Tokyo 152, Japan;Department of Materials Science and Engineering, Case Western Reserve University, Cleveland, Ohio 44106;Department of Materials Science, Tokyo Institute of Technology, Yokohama 227, Japan |
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| Abstract: | Vickers hardness in spinel increases by 23% after neutron irradiation to a fluence of 8.3 × 1022 n/m2 at 100°C. Annealing at high temperatures above 100°C gradually decreases the hardness. Above 500°C, the hardness is reduced to almost the same value as that of unirradiated material. The hardness of spinel, irradiated at 470°C to a fluence of 2.4 × 1024 n/m2, is unchanged both after irradiation and after annealing up to 1000°C. The length change during annealing was also measured and is similar to the hardness change. Frank dislocation loops with a density of 3 × 1014/cm3 are induced by neutron irradiation at 470°C but they apparently do not affect the hardening in spinel. Thus, point defects are concluded to act as obstacles against dislocation movement. The yield stress measured at 1400°C is also unchanged after irradiation. It is believed that not only the point defects but also the loops are annihilated by annealing at 1400°C. |
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| Keywords: | hardening spinels dislocations irradiation defects |
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