Short-time high-temperature annealing of Fe(CuMo)SiB: a Mِssbauer study

The very soft magnetic properties of the Fe73.5Cu1Nb3Si13.5B9 (FINEMET) alloy are due to a nanocrystalline structure built during the annealing of the as-quenched amorphous ribbon at suitable chosen temperature and time. In the nanocrystalline state, the samples consist of nanoscale FeSi grains with diameters between 10 and 15 nm embedded in a remaining amorphous matrix. The formation of the nanostructure is influenced by the elements Cu and Nb. In this contribution, Nb is replaced by Mo, an atom with a smaller diameter. The aim of this experimental study is to investigate the changes in the onset of nanocrystallization, the microcrystallization and also the crystallization products due to the replacement of Nb by Mo. nventional Mِssbauer effect on 57Fe is used as a tool for phase analysis. The phase identification is done via the hyperfine field values. We are able to perform well defined annealing procedures for short times, i.e., 15, 30, 60, 90, 120, 180, 300 and, for comparison, 3600 s. This time series was performed at a rather high annealing temperature of 650 °C. After the annealing procedure, the samples were rapidly cooled down to room temperature. The Mِssbauer spectra are collected after this procedure.