STUDY OF Ni-Cr-Fe AUSTENITES, FERRITES AND FE-B MELT-SPUN ALLOYS USING THE MOSSBAUER EFFECT

This dissertation represents the work carried out at the Mossbauer Spectroscopy Laboratory, PINSTECH, Pakistan. The work was concentrated on four main fields of materials research. The Ni-Cr-Fe austenites have been studied to investigate the cause of line broadening and the lattice dynamics. Measurements have been made on the spalling of SS-304L formed in air and steam at 1200°C, to identify the corrosion products and to study the effect of exposure time on their oxidation behavior. The products formed due to prolonged (three years) exposure of mild steel to deionized water have been studied and α-FeOOH has been identified as a phase ever detected in such conditions. A new kind of magnetic ordering in ferrihydrite, an intermediate corrosion product, has been recognized. The Ni-Zn and Mn-Zn ferrites have been studied to investigate the cation distribution and its effect on the magnetic ordering. The Fe-B melt-spun alloys have been studied to investigate the crystallization through their isochronal heat treatment