Papers by Author: X.Y. Sun

Abstract: The local environment issued from the phase decomposition in Fe-25Cr-12Co-1Si alloy during step ageing has been studied by 57Fe Mössbauer spectrometry. The phase decomposition is influenced by both ageing time and temperature. It processes rapidly when ageing temperature is high. The formation of different kinds of (Fe, Co)-rich, Fe-rich and Cr-rich domains with independent hyperfine parameters during phase decomposition was characterized by hyperfine field distribution. The magnetic hardening of the alloy was discussed basing on single domain particle model.

Abstract: Magnetic stability of a Fe-Cr-Co permanent magnet material at high temperatures has been investigated. Changes of microstructures and hyperfine field distributions after high temperature holding were analyzed by transimission electron microscopy (TEM) and Mössbauer spectroscopy. The results of experiments indicate that the changes of magnetic properties of the Fe-Cr-Co alloy tend to decrease, and then gradually keeps a certain level with increasing the holding time at high temperature. TEM observations show that microstructures of the alloy do not change distinctly after high temperature holding. Hyperfine interaction study through Mössbauer spectroscopy finds that the composition difference between α1 and α2 phases increases, and the composition of the two phases fluctuates. This study attributes the change of magnetic properties to element redistribution of Cr atom rather than the change of microstructure.