Weiterentwicklung einer AlSi8Cu3-Legierung für den anwendungsspezifischen Einsatz im Kokillengießen

Rising requirements in lightweight-area and decrees which define low emission of cars initiate new materials in automobile segment. One solution for reducing the weight of cars is the use of aluminum alloys. The problem on commonly used aluminum alloys for engine is, that they are non-resistant compared to intercrystalline corrosion and because of the included Copper (Cu). Furthermore they have low mechanical properties at elevated temperature up to 250 °C. The formation of the microstructure from hypoeutectic aluminum alloys and the intermetallic precipitation are one of the main reason for the casting, thermomechanical and thermophysical properties. While operation temperature in engine the precipitation begin to grow (Ostwald- maturing) and the microstructure lose their thermic durability. In fact of the mentioned it is important to develop aluminum alloys with low corrosion-impact and high mechanical properties at elevated temperature. The aim of these project is to develop an high-temperature- and corrosion-resistant aluminum alloy with an maximum level of 0,5 Ma.-% Cu. In this context an AlSi8Cu0,5 will be the base for six test-alloys which include define amounts of cobalt (Co), vanadium (V) and chrome (Cr). Before named test-alloys will compared to four reference-alloys like the AlSi8Cu0,5 – an copper-reduced AlSi8Cu3 –, the AlSi9Cu3(Fe) – an alloy which is used for engine –, the Thermodur-72 (AlMg7Si3Mn) from Rheinfelden alloys and the AlSi8Cu3 as an direct reference to the test-alloys. An profile with requirements for power train parts is the base for the constructive tests. At first the whole alloys get an heat treatment in an over-aged condition to simulate the impact of define engine operation. After that the mechanical properties will checked with tensile testing machine at room temperature and at 250 °C and the low cycle fatigue is also an important criterion. The physical properties can be rated with tests which quantify the thermal expansion and the thermal conductivity. The castability will be probed with common instruments. The evaluation of the effects will compared with the microstructure and existent intermetallic phases. So the additional value can be attributed to heat consistent precipitation generated through define amounts of Co, V and Cr.