Inverse segregation
Tóm tắt
Inverse, segregation at the chill face and the region adjacent to the chill face has been calculated for the AlCu,AlZn, and SbBi alloys using a finite difference analysis. In the calculations the effect of changes in composition and temperature, as well as the volume change on freezing, were considered during the solidification process. The calculations agree in general with the reported values of chill face segregation in the AlCu and SbBi alloys. They differ appreciably in the 40 pet composition region of the AlZn alloy, where a depression in the chill face segregation/composition curve is obtained instead of a peak. In the region adjacent to the chill face, the inverse segregation is found to drop rapidly with distance from the face, the rate decreasing with increasing solute concentration. The presence of an air gap between the solidifying metal and the chill can markedly influence the chill face and adjacent segregation. The air gap size in turn is dependent on the pouring temperature of the melt and the chill material. In one case the calculated air gap size was 3 Μm.
Tài liệu tham khảo
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