Young's Modulus of Al-Si-Mg-Cu Based Alloy Under Different Heat Treatment Processes

Young's modulus of metallic materials is one of the most important mechanical properties in controlling structural design. The increase of Young's modulus in cast aluminium alloys is attractive for lightweight structures. In the present investigation, the Young's modulus of an Al-Si-Mg-Cu alloy reinforced with TiB2 and Mg2Si phases was investigated under different heat treatment processes, including T4, T6, T7 and O. The microstructural evaluation and mechanical properties of the developed Al-Si-Mg-Cu alloys were examined by X-ray diffractometer (XRD), scanning and high resolution transmission electron microscopes (SEM and HRTEM), ultrasonic pulse technique and tensile test. The results revealed that the alloys, in all heat treatment conditions, mainly consist of Si, Mg2Si and TiB2 phases, which are responsible for the increase of Young's modulus. HRTEM micrographs showed the formation of incoherent, clean and smooth interfaces between aluminium matrix and TiB2 particles. The alloys with over 90 GPa Young's modulus are still castable for making shaped castings. In comparison with the conventional aluminium alloys that have Young's modulus at a level of 70 GPa, 30% increase of Young's modulus can be achieved by the developed alloys.