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前言过共晶铝硅合金的热膨胀系数较小,耐磨性好,有足够高的强度,耐热性也较好,可作为高速大马力发动机的活塞材料。目前国外汽车坦克发动机的活塞已广为使用。但由于这种合金含硅量较高、其金相组织由大针状的共晶硅、大块的初晶硅及α铝固溶体等相组成。这种组织会降低合金的机械性能,恶化合金的补缩性能,切削加工性能也较差。所以在推广使用过共晶铝硅合金时,首先遇到的关键,便是在熔化过程中,如何对
Preface Hypereutectic Al-Si alloy has small thermal expansion coefficient, good wear resistance, high enough strength and good heat resistance, which can be used as the piston material of high speed and high horsepower engines. At present the piston of the foreign car tank engine has been widely used. However, due to the higher silicon content of the alloy, the microstructure consists of a large needle-shaped eutectic silicon, a bulk of primary silicon and an α-aluminum solid solution phase. This organization will reduce the mechanical properties of alloys, deterioration of alloy shrinkage performance, cutting performance is also poor. Therefore, the promotion of the use of eutectic Al-Si alloy, the first encounter is the key, that is, in the melting process, how to