Effect of Si and Cr on stacking fault probability and damping capacity of Fe-Mn alloy

The stacking fault probability and damping capacity of Fe-19Mn, Fe-17Mn-2Cr and Fe-19Mn-1.5Si alloys were studied. The stacking fault probability and volume fraction of ɛ-martensite were determined using XRD. The damping capacity was measured using reversal torsion pendulum. The microstructure was observed using optical microscope and TEM. The results indicated that the damping capacity of three alloys increased almost linearly with increasing strain amplitude. This could be explained using the breakaway model of Shockley partial dislocations. Si could increase the stacking fault probability and the number of Shockley partial dislocations of Fe-Mn alloy, but it decreased the damping capacity because it introduced much distortion of lattice that pinned down the movement of Shockley partial dislocations. Cr decreased the damping capacity of Fe-Mn alloy too, but its effect was not heavier than Si. This was because that the distortion of lattice after adding Cr is not more serious than adding Si.