Study on the eutectic modification level of Al-7Si Alloy by computer aided recognition of thermal analysis cooling curves

The effect of Sr content on the Al-7Si solidified microstructure was investigated. And the eutectic silicon modification level assessment of Al-7Si alloys was studied combined with the computer aided cooling curve pattern recognition method. It has found that the eutectic silicon modification level of Al-7Si alloy increases with the increase of Sr content. The eutectic structure is fully modified when the Sr content reaches 56 ppm. While the modifier addition is given, the modification level decreases with the increasing of holding time. When the modifier addition is small, the modification level decreases with the increasing of holding time. But when the Sr addition is at a higher level, the modification level sustains at the initial period of holding time, and then decreases with the holding time. The results of modification level assessment show that the modification level difference converges to zero when the comprehensive parameter, which expresses the difference between cooling curves, approaches to zero. The whole shape of the solidification segment of a thermal analysis cooling curve can token the eutectic silicon modification level of the Al-7Si alloy melt. The modification level can be precisely assessed by comparison of the cooling curve of the melt to be evaluated with those in a database to find the one most similar to it. Based on a database established from a large amount of experimental results, the on-line prediction of eutectic modification level of Al-7Si alloy melt has been realized. (c) 2006 Elsevier B.V. All rights reserved.