Rates of transformations in the ferrosilicon system
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Mössbauer spectroscopy has been used to determine the time-temperature-transformation diagram (TTT) for the eutectoid transformation in the silicon rich part of the Fe−Si binary system. Studies of TTT-diagram of samples consisting of 55 and 75 weight percent Si respectively have been carried out in nominally pure samples as well as commercial ones. Under equilibrium conditions these represent two phases, the zeta-alpha phase and the zeta-beta phase. The former is a high temperature, phase whereas the latter is stable below about 967°C. The eutectoid transformation from alpha into beta phase involves changes in crystal structure and a complete change in the vacancy distribution characterizing the alpha phase. Mössbauer spectra of samples involved were fitted, according to former results, with two well defined doublets characterizing the beta phase and two broad line doublets attributed to the more complicated alpha phase. The paper proposes a model explaining the relationship between thermal history and material strength in the system.
KeywordsSilicon Thin Film Crystal Structure Equilibrium Condition Binary System
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