| 200㎛ thick Ta thin sheets and Fe-C-(Si) alloys with different chemical compositions, and interfacial reaction was investigated. The growth of carbide layer formed at the interface were cast-bonded after isothermal heat treatment at 1173K, 1223K, 1273K and 1323K for various times was investigated. The carbide formed at the interface was TaC, its chemical composition was 91.5wt.%Ta-6.6wt.%C-1.9wt.%Fe, and its hardness was ranging from 1820 to 1970Hv. The thickness of TaC layer was increased linearly in proportional to the heat treating time. Therefore, it was suggested that the growth of TaC layer was controlled by the interfacial reaction. The growth rate constant of TaC layer was slightly increased with increase of carbon content when the silicon content is similar in the cast irons. However, as silicon content increases with in case of almost same amount of carbon content, the growth of TaC layer was greatly retarded. The calculated activation energy for the growth of TaC layer was varied in the range of 278.1∼329.1kJ/㏖ with the compositions of cast irons. The activation energy was shown to be a tendency to increase with an increase of silicon content in cast iron. |
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