Effect of Catalyst on Heterogeneous Nucleation in Fe-Ni-Cr Alloys

摘要

In order to elucidate the nature of heterogeneous nucleation, a differential scanning calorimetry (DSC) thermal analysis of Fe-Ni-Cr alloys (Ni + Cr content=30 mass percent (constant); Ni content: 7.5 to 29.3 mass percent) containing TiN and AI_2O_3 was conducted. Then, special attention was paid to the difference in the phase of the primary crystal nucleated by the triggering effect of a catalyst (nucleating agent). The solidification and transformation mode appearing during cooling in these alloys is classified into three cases: F mode, FA mode, and A mode. The change of modes and the critical undercooling (AT) depend on the kind of catalyst used as well as on the chemical composition. In addition, in spite of the kind of primary crystal, the value of DELTA T is always smaller in the order of TiN