STUDIES OF REFINED HIGH STRENGTH CAST HYPEREUTECTIC Al-Si ALLOYS

Abstract

The automotive/aerospace industry is currently working to accommodate the conflicting requirements of both environmental legislation, and customer demands for greater performance and more luxury and safety features, by developing a lightweight and energy-efficient vehicle. A significant proportion of efforts are currently being directed toward the substitution of aluminium for steel in the body structure as the body accounts for 20±03% of the total weight of the vehicle. Cast hypereutectic Al-Si alloys are very attractive for automotive and aerospace industry due to good wear resistance and high strength to weight ratio. Attempts have been made worldwide to further enhance the mechanical and tribological performance and ease of fabrication of these alloys by using variety of approaches. Out of these approaches, Si particle refinement technique has been more commonly used to refine the size of primary silicon in hypereutectic Al-Si alloys for achieving above objectives. Because as cast hypereutectic Al-Si alloys generally contains large primary polyhedral shaped primary silicon particles in matrix of Al-Si eutectic. Presence of coarse primary silicon particles in hypereutectic Al-Si alloys lowers its machinability, mechanical and tribological performance. In present study, the effect of barium as a silicon particle refiner has been carried out. Results show that the mechanical and tribological performance of the alloy is improved with the use of barium as a refiner.