Development of a new ductile heat-treated multi-component aluminium by HPDC with high-performance properties for temperature applications

This research aims to develop heat treatments to improve mechanical and thermal properties for a novel, heat-treatable patented multi-component AlMgSiCu aluminium produced using the High-Pressure Die Casting (HPDC) process. For this purpose, experiments were designed to investigate various parameters related to the thermal treatments, implemented in three stages. The alloy displayed excellent mechanical properties at room temperature (RT) and 200 ºC with an adjusted and optimized heat treatment: 440 °C solution treatment for 72 hours, hot-water quenching, and natural ageing. The alloy's microstructure consisted of an aluminium matrix with primary and eutectic Mg₂Si and globular Al₂CuMg phases, where all Al₂Cu phases were transformed into Al₂CuMg. The thermal transformation of Al₂Cu into the most stable Al₂CuMg phase, significantly enhanced the alloy´s overall properties, resulting in a 40 % increase in elongation (E) under tension with a yield strength (YS) of 221 MPa, an ultimate tensile strength (UTS) of 244 MPa, and an E of 1.1 %. Additionally, it led to a 20 % improvement in ultimate compressive strength (UCS), with a 60 % increase in compressive deformation (D) at RT compared with as-cast samples. At 200ºC the tensile properties remained stable, with a YS of 226 MPa, UTS of 254 MPa, and E of 1 %, while the UCS decreased by 30 % and both YS and D remained constant with a YS of 211 MPa, UCS of 468 MPa and a D of 25.1 %. Overall, the alloy demonstrated excellent performance, achieving some of the most favourable strength-to-density ratios at 200 ºC.