Effect of order-disorder transition on magnetic properties of rapidly soldified high silicon-iron ribbons
The effect of ordering on the soft magnetic properties of 6.5% silicon-iron ribbons obtained by rapid solidification is studied. The atomic order cannot be prevented by the fast cooling. It is shown that isothermal aging at 700 degrees C induces a small decrease in coercive force and hysteresis losses, while aging at 500 degrees C induces an increase in these parameters. The magnetic evolutions are corroborated by Lorentz microscopy observations. The values obtained and the observations suggest a weak individual interaction, which may be due to local variation of exchange and anisotropy energy. >
Effect of atomic order on the electrical and magnetic properties of Fe/sub 100-x/Si/sub x/ (6 < x < 14) alloys
The influence of the degree of atomic order on the electrical and magnetic properties of Fe-Si alloys with different Si-contents was determined. Five different Fe-Si alloys with Si-contents ranging from 6-14 at%Si were annealed from 500 to 1100/spl deg/C for 2 h and then quenched in water in order to develop different degrees of order. /sup 57/Fe Mossbauer spectra were obtained in order to determine the type and degree of order. Differential scanning calorimetry was performed to detect the disorder/order transition. The disordering in the samples greatly increase the electrical resistivity. Moreover, losses increase with annealing temperature due to the generation of internal stresses and/or creation of disordering.
Changes in Quartz During Heating and the Possible Effects on Si Production
In Si and FeSi production, the main Si source is SiO2, in the form of quartz. Reactions with SiO2 generate SiO gas that further reacts with SiC to Si. During heating, quartz will transform to other SiO2 modifications with cristobalite as the stable high-temperature phase. Transformation to cristobalite is a slow process. Its rate has been investigated for several industrial quartz sources and has been shown to vary considerably among the different quartz types. Other differences in behavior during heating between these quartz sources, such as softening temperature and volume expansion, have also been studied. The quartz-cristobalite ratio will affect the rate of reactions involving SiO2. The industrial consequences and other implications of the observed difference between quartz types are discussed. Initial studies of industrial quartz were published by Ringdalen et al. In the current work, a new experimental method has been developed, and an investigation of several new quartz sources has confirmed the earlier observed large variation between different sources. The repeatability of the data has been studied and the effect of gas atmosphere investigated. The results from the earlier work are included as a basis for the discussion.