Mossbauer and electron microscopy study of martensitic transformations in an Fe-Mn-Mo alloy

Abstract

The kinetic, morphological, crystallographic, and magnetic characteristics of thermally induced martensites in Fe-13.4wt% Mn-5.2wt% Mo alloy were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Mossbauer spectroscopy. The experimental results reveal that two types of thermal-induced martensites, epsilon (hcp) and alpha' (bcc) martensites, are formed in the as-quenched condition, and these transformations have athermal characters. Mo addition to the Fe-Mn alloy does not change the coexistence of epsilon and alpha' martensites with the Mn content between 10wt% and 15wt%. Besides, Mossbauer spectra reveal a paramagnetic character with a singlet for the gamma (fcc) austenite and epsilon martensite phases and a ferromagnetic character with a broad sextet for the alpha' martensite phase. The volume fraction of alpha' martensite forming in the quenched alloy is much more than that of the epsilon martensite.