Mössbauer studies on athermal martensite formation in an fe-ni-mn alloy

Abstract

In this study, austenite-martensite phase transformations which are formed by cooling effect in Fe-30% Ni-0⋅ ⋅2% Mn alloy are investigated with Mössbauer spectroscopy and scanning electron microscopy. The single peak of the paramagnetic phase and the six peaks of the ferromagnetic phase of Fe-30% Ni-0⋅ ⋅2% Mn alloy were observed in the Mössbauer spectrum. The internal magnetic field strength of ferromagnetic martensite phase was determined as 33⋅ ⋅8 T and the isomer shift values were determined as-0⋅ ⋅11 mm⋅ ⋅sec-1 and-0⋅ ⋅06 mm⋅ ⋅sec-1 , respectively, for the austenite and martensite phases. In this alloy, athermal transformation was observed. The results obtained are in agreement with literature.

Martensitic transformation and magnetic properties of Fe–24·5%Ni–4·5%Si alloy

“…On the other hand, Mo ¨ssbauer spectroscopy is known as one of the useful and most sensitive techniques to clear out the magnetic characters of the material and to estimate the volume fractions of austenite and martensite phases. [16][17][18][19] The Mo ¨ssbauer effect is a well known resonance absorption effect created by c rays owing to the change in the energy levels of atomic nuclei and also can determine isomer shift values and internal magnetic field of martensite. 4 Although it is well known that martensite volume fraction increases with increasing austenitising temperature and cooling rate, there has been no study reported about the effect of martensite amount on the magnetic properties of alloys.…”

Comparison of thermally induced and deformation induced martensite in Fe–29% Ni–2% Mn alloy

“…In a previous study of authors [27], lath martensite morphology is observed in the austenite phase of 14 h homogenized Fe-30% Ni-0.2% Mn alloy after the current thermal affect. In the present study, thermally induced martensite showed a morphologic variety from partially twinned lenticular (denoted with symbol ␣ with a bcc crystal structure in Fig.…”

Deformation induced martensite characteristics in Fe–29Ni–2Mn alloy

“…[10][11][12][13][14] From a morphological point of view, reported results for ferrous martensite compromises that a variety of morphologies, i.e. lath, butterfly, lenticular and thin plate 2,15-18 can be seen within thermally induced transformations for different alloy compositions.…”

“…14,[20][21][22] This case is also generalised by Shimizu and Kakeshita 1 as that many ferrous alloys and steels undergoing martensitic transformation are paramagnetic or ferromagnetic in the austenitic state, but they are all ferromagnetic in the martensitic state.…”