| This work was carried out in order to investigate the effects of the grain size and vacancy on the Ms temperature of an austenitic Fe- 33%Ni alloy. The Ms temperature was raised with increasing the austenitizing temperature within the range from 850℃ to 1150℃, owing to the grain growth and the vacancy concentration. It was observed that the larger was the austenite grain the higher was the Ms temperature. The influence of the austenite grain size was similar to that of the austenitizing temperature. With regard to the effect of vacancy, the Ms temperature was increased with increment of quenching temperature below 900℃, but was lowered above 1000℃. Meanwhile, the specimen which was quenched at 900℃ contained the straight dislocations and the sample which was heat-treated at 1150℃ included the curved dislocations with the coalesced vacancies. From the above results, it was concluded that the Ms temperature was mainly dependent upon the austenite grain size and the dislocation pinning with vacancy arrangements. |
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