The Contribution of Dislocation - Impurities Interaction to Kinetics of Martensitic Transformation of Quenched f.c.c. Fe-Ni-Mo Alloys

The kinetics of martensitic transformation in austenitic Fe-Ni-Mo alloys depends on the carbon content. Analysis of carbon redistribution between f.c.c. solid solution and dislocation has been carried out with the help of internal friction (amplitude and temperature effects) study and stress relaxation tests. The martensitic transformation was proved by magnetic induction and thermal differential analyses. The increase of carbon content in quenched austenitic alloys leads to the saturation of dislocation atmospheres and to the supersaturation of f.c.c. solid solution. The type of martensitic transformation (athermal or isothermal) kinetics depends on different relaxation resistance of austenite which is controlled by different dislocation pinning degree. The strong correlation between the degree of dislocation pinning, the type of martensitic transformation and the stress relaxation effect allows to make the conclusion that the dislocation mobility plays an important role in the nucleation and formation of the low temperature structure of Fe-Ni-Mo alloys.