Ultrafine-Grained Structure of Fe-Ni-C Austenitic Alloy Formed by Phase Hardening

The X-ray and magnetometry methods were used to study α–γ transformation mechanisms on heating quenched Fe–22.7 wt.% Ni–0.58 wt.% С alloy. Variation of heating rate within 0.03–80 K/min allowed one to switch from diffusive to non-diffusive mechanism of the α–γ transformation. Heating up primary austenitic single crystal specimen at a rate of less than 1.0–0.5 K/min has led to formation of aggregate of grains with different orientation and chemical composition in the reverted austenite. Significant fraction of these grains was determined to have sizes within nanoscale range.