The effect of Ti content on α martensite phase transformation, and magnetic properties by Mössbauer spectroscopy in Fe-30%Ni-x%Ti (wt%) alloys

In this study, the influence of Ti content on the microstructure of the martensite bcc α'), which was formed by thermal effect, was investigated by scanning electron microscope and transmission electron microscope observations, in Fe-30Ni-xTi (x=0.8, 1.8, 2.6) alloys. The crystallographic orientation relationship between austenite fcc (γ) and thermally induced bcc (α') martensite was found to be as (111)_{γ}/(011)_{α} (Kurdjumov-Sachs (K-S)), by the electron diffraction analysis. The martensitic transformation temperature (M_{s}) of α' martensite was determined as -41°, -62°, and -76 ° in the alloys with 0.8%, 1.8%, and 2.6% Ti concentration, respectively. The Mössbauer spectrometer analysis has been revealed by a paramagnetic character for the austenite phase and magnetically order character for α' martensite phase. Hyperfine magnetic field, isomer shift and volume fractions of phases were determined by the Mössbauer spectroscopy.