Effects of alloying elements on mechanical and thermal characteristics of Al-6wt-%Si-0.4wt-%Mg–(Cu) foundry alloys

The objective of this study was to investigate the effects of alloying elements on mechanical and thermal characteristic of Al-6wt-%Si-0.4wt-%Mg-(Cu) foundry alloys after heat treatment using a universal testing machine and a laser flash apparatus. Solid solution treatment of samples was carried out at 535 degrees C for 6 h before quenching samples in warm water. Artificial ageing treatment was conducted at various temperatures ranging from 180 to 220 degrees C for 5 h. When Cu was added to increase the mechanical strength of Al-6wt-%Si-0.4wt-%Mg alloy, its thermal conductivity decreased. After adding 0.1wt-%Ti to an Al-6 wt-%Si-0.4wt-%Mg-0.9wt-%Cu alloy, ultimate tensile strength (UTS) was improved 18 MPa compared to that of Ti-free alloy at ageing temperature of 180 degrees C. The addition of Ti facilitated the formation of theta '-Al2Cu and Q '-phase, which resulted in increased UTS at room temperature. In the case of Cu-free Al-6wt-%Si-0.4wt-%Mg alloy, adding Ti to the alloy did not affect the UTS.