Development of Hypereutectic Aluminum-Silicon Alloys for High Pressure Die Casting

The current paper presents the results of the experimental program to develop of hypereutectic aluminum-silicon alloy similar to the 390 alloy for high pressure die casting. Calcium and zirconium were respectively used as eutectic silicon modifier and primary silicon refiner. Calcium, once considered deleterious because of its effect on the properties of aluminum alloys, is now considered beneficial in many ways. The addition of calcium decreases the nucleation temperature of the primary silicon, thus makes the developed alloy suitable for high-pressure die casting avoiding the problems such a reduced die life, due to a thermal fatigue and abrasion. In addition, a low pouring temperature of new hypereutectic die casting alloy minimizes the risk of the melt spurting out of the die and appearance of hot tearing. The optimum alloy and process parameters of the high pressure die casting process were selected by a designed die which contains test samples for measurement of hot tearing resistance, die sticking tendency, mechanical properties and abrasive wear. Effects of filling conditions on microstructure and mechanical properties of AlSi17Cu4 with combinations of Ca and Zr are discussed.

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