Nanostructurization of Fe-Ni Alloy

Data about an effect of cyclic.gamma-a-gamma. martensitic transformations on the structure state of reverted austenite Fe-31. 7 wt.% Ni-0.06 wt.% C alloy are presented. The effect of multiple direct.-a and reverse a-gamma. martensitic transformations on fragmentation of austenitic grains has been investigated by electron microscopy and X-ray diffraction methods. An ultrafine structure has been formed by nanofragmentation inside the initial austenite grains due to the successive misorientation of their crystal lattice. Austenite was nanofragmented as a result of multiple.gamma-a-gamma. martensitic transformations. Slow heating of the nanofragmented alloy at a rate below 2 degrees C/s results in nanograin refinement of the structure by multiplication of the reverted.-phase orientations. The conditions of structure refinement up to ultrafine and nanocrystalline levels as a result of both shear and diffusion mechanisms of reverse a-gamma. transformation are determined.