Fe-Ni-C合金中珠光体、贝氏体及马氏体的相变内耗

通过研究三种 Fe-Ni-C 合金中珠光体、贝氏体及马氏体的低频相变内耗,发现马氏体相变内耗遵守相界面位错的静滞后损耗机制,珠光体和贝氏体相变内耗不遵守这种机制。在频率基本不变时,随着冷却速度的增加珠光体和贝氏体的相变内耗峰增高,峰温降低,且 Q(?)和(?)/fm 件·T_m 呈正比线性关系;频率增加时,珠光体和贝氏体的内耗峰明显降低,峰温上串。在连续冷却条下,Fe-Ni-C 合金中开始珠光体及贝氏体相变时并不存在点阵软化现象。

THE INTERNAL FRICTION OF THE PEARLITIC BAINITIC AND MARTENSITIC TRANSFO-RMATIONS IN Fe-Ni-C ALLOYS

The low frequency internal friction of the pearlitic,bainiticand martensitic transformations in three Fe-Ni-C alloys has been studied.Theresults show that the internal friction of the martensitic transformation is incorrespondence with the model based on the hysteresis loss mechanism associ-ated with stress-induced motion of the interface dislocation,while that of thepearlitic and bainitic transformations does not obey this model.At a constantfrequency,the internal friction peaks of the pearlitic and bainitic transforma-tions increase as the cooling rate increases, but the temperature of the internalfriction peaks decreases,and the (?) is directly proportional to the (?)/f_mT_m.When the frequency increases,the (?) of the pearlitic and bainitic transfor-mations lowers apparently,and the temperature of the damping peaks increases.It was revealed that,at the begining of the pearlitic and bainitic transforma-tions under continuous cooling,there is no lattice softening.The internal fric-tion of the isothermal bainitic transformation in a Fe-Ni-C alloy has alsobeen studied,which proves that there appears a damping peak in the incubationperiod,and the damping peak may be attributed to the nucleation ofbainite.Consequently it infers that the mechanism of the bainite reaction seemssimilar to that of pearlite.