Dynamic temperature resistometry analysis of rapidly quenched Fe 86B 14 alloy and its correlated study by Mössbauer spectroscopy and scanning electron microscopy

Abstract

Dynamic temperature resistometry has been used in order to characterize the stability and crystallization behaviour of amorphous Fe 86B 14 alloy prepared by the single-roll melt spinning technique in a helium atmosphere at constant heating rates (17, 40, 80 K h −1) from room temperature to 900 K. The crystallization temperature first increases and then decreases with the increase in heating rate. The data were recorded in forward and reverse directions, indicating different behaviour in the amorphous region. Mössbauer spectroscopy was used to study various steps involved in the resistivity-temperature (RT) curve and corresponding phases formed on samples air quenched after being exhibited subjected to the same heat treatments. The as-received sample exhibited some percentage of γ-Fe phase up to the last temperature; however, its value increases as crystallization proceeds. The first product phase formed from the amorphous matrix was observed to be α-Fe, followed simultaneously by metastable Fe 3B and Fe 2B, resulting in a rapid decrease in resistivity. Fe 3B breaks into α-Fe and Fe 2B at higher temperatures, which is also highlighted by a steep and sudden fall in the RT curve. The percentages of these final phases almost remain constant up to the final temperature which is in agreement with the linear rise of the RT curve. Scanning electron microscopy analysis revealed the presence of round and ribbon-shaped zones in amorphous areas in the as-received sample which break up into pieces on heating.