Effects of Nb and C in solution and in NbC form on the transformation-related internal friction of Fe-17Mn (mass%) alloys

The effects of presence of Nb and C in solution or in the form of NbC precipitates on the transformation of binary Fe-17mass%Mn alloys were evaluated from micro structural and macroscopic point of view. At microstructural level precipitation of NbC was accompanied by the decrease of both relative amount Of E martensite and martensite plate thickness. The precipitation was associated with a general increase of proof stress and thermal hysteresis on the internal friction curves as well as a decrease of the maximum value of internal friction, caused by martensitic transformations, as evaluated by means of a dynamic mechanical analyzer. The solute atoms slightly reduced internal friction and the NbC precipitates markedly reduced internal friction, probably due to the pinning effect on the oscillated motion of Shockley partial dislocations.