铝基复合材料凝固成核的差示扫描量热法(DSC)研究

DSC STUDY OF THE NUCLEATION PHENOMENON IN ALUMINUM METAL MATRIX COMPOSITES

采用DSC方法研究了增强相对铝合金成核过程的影响。对基体合金与复合材料凝固临界温度的测量结果表明,增强相会抑制α-Al相的析出;增强相之间间隙尺寸越小,α-Al相析出的过冷度越大。α-Al不能在增强相表面非均质成核。与α-Al相不同,初晶硅相析出的过冷度在增强相存在的情况下减小,表明增强相可以作为初晶硅相成核的衬底。DSC方法可以有效地用来研究复合材料的成核现象。

The effect of the added reinforcement on the nucleation process of aluminum alloys was studied by a differential scanning calorimetry (DSC). The onset temperature measurement of monolithic alloys and composites reveals that the nucleation of the aluminum phase is restricted with the presence of the reinforcement. In addition, the undercooling of α-Al phase precipitation increases with the decrease of inter-fiber spacing. So α-Al phase cannot preferentially nucleate and grow on the reinforcement surface. In contrast to α-Al phase, the undercooling of primary silicon precipitation decreases with the presence of the reinforcement, which shows that the reinforcement can act as the preferential nucleation site for the primary silicon. It is effective to study the nucleation phenomenon of aluminum metal matrix composites by the DSC.