Effects of Al-5Ti-0.62C-1.07La intermediate alloy on the microstructure and mechanical properties of A356 aluminum alloy

The physical characters that belong to hypo-eutectic Al-Si alloys are affected by certain important factors including the dimension, distribution together with structure of eutectic Si crystals together with primary α-Al. In this paper, A356-x Al-5Ti-0.62C-1.07La (x = 0, 4, 5, 6, 7 wt%) alloys are was prepared by mechanical stirring. The effects of Al-5Ti-0.62C-1.07La intermediate alloy on the microstructures and mechanical properties of A356 alloy are investigated. Results show that the primary α-Al was significantly refined by Al-5Ti-0.62C-1.07La intermediate alloy. The secondary dendrite arm space (SDAS) of unrefined α-Al is approximately 40 μm. When the substance of Al-5Ti-0.62C-1.07La intermediate alloy is 6 wt%, SDAS declines to 10 μm. In addition, the component part of eutectic Si turns from thick acicular/schistose to short rod-like together with a section of pellets. Adding 6 wt% Al-5Ti-0.62C-1.07La intermediate alloy, A356-T6 alloy obtained the best tensile function and hardness. The ultimate tensile strength (UTS), elongation (El) together with Vickers hardness (HV) are 183.5 MPa, 8.2% and 62.3, which is increased by 30.3%, 95.2% and 38.1%, respectively. Furthermore, the variation in mechanical properties change with the development of micro-structure. (paper)