Thermally activated martensite formation in ferrous alloys

Magnetometry was applied to investigate the formation of α/α´martensite in 13ferrous alloys during immersion in boiling nitrogen and during re-heating to room temperature at controlled heating rates in the range 0.0083-0.83 K s^-1. Data showsthat in 3 of the alloys, those that form {5 5 7}_γ martensite, no martensite developsduring cooling. For all investigated alloys, irrespective of the type of martensiteforming, thermally activated martensite develops during _heating. The activationenergy for thermally activated martensite formation is in the range 8‒27 kJ mol^-1and increases with the fraction of interstitial solutes in the alloy