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In this research paper, the effect of the addition of copper (0.02 to 3.32 wt.%) on microstructure, mechanical and thermal properties of Al-Zn-Mg alloy are studied using an optical microscope, scanning electron microscope (SEM), X-ray diffractometer (XRD), Vicker’s microhardness tester, universal testing machine (UTM) and differential scanning calorimeter (DSC). Precipitates (η-MgZn2phases) are present in as-cast Al-Zn-Mg alloy. SEM and XRD analyses have shown the presence of η (MgZn2) and θ (Al2Cu) precipitate in the as-cast Al-Zn-Mg-Cu alloy. Micro-Vickers hardness increases from 121.3 HV1 to 153.1 HV1 for the initial increase in copper content (0.02 to 1.54 wt.%) and then decreases to 137.3 HV1 (3.32 wt.% copper). The melting point decreases continuously with increased copper content from 619.8 °C (0.02 wt.% Cu) to 608.5 °C (3.32 wt.% Cu). Peak compressive stress, absorbed energy per unit volume, yield stress is observed to increase by 43.6%, 75.4%, and 59.3%, respectively, for the rise in copper content (0.02 wt.% to 1.54 wt.%) in the alloy.

This research paper examines the effect of different solution heat treatments parameters (temperature and time) on Al–3.39%Cu–2.26%Mg (wt%) alloy’s microstructure, thermal, mechanical and corrosion properties. 5754 alloy and Al–Cu alloy are used to make Al–3.39%Cu–2.26%Mg (wt%) by gravity die casting. Solution heat treatment at different temperature and time (500 °C-10 min, 500 °C-4h, 530 °C-10 min and 530 °C-2h). As-cast Al–Cu–Mg alloy have α-phase and eutectic phase. After solution heat treatment and aging, precipitates phases is observed in microstructure. X-ray diffraction analysis results have shown that a precipitate phase [S phase (Al2CuMg)] gets formed in as-cast conditions but undergoes dissolution during the solution heat treatment process. As-cast Al–Cu–Mg alloy has a Brinell hardness value of 77.2 HB. As-cast alloy has S (Al2CuMg) precipitate phase increases hardness by precipitation strengthening. After solution heat treatment and aging, Brinell hardness reduces. After solution heat treatment (500 °C for 4 h) and aging (200 °C for 5 h), Brinell hardness values becomes 63.6 HB (− 17.6% decrease). Corrosion resistance improves after the solution heat treatment due to the dissolution of the precipitate phase, forming an almost single-phase solid solution. The as-cast alloy exhibits a peak compressive stress of 494.2 MPa, which increases after solution heat treatment and water quenching to 572.7 MPa (without aging). After aging, peak compressive stress decreases to 508.4 MPa. Failure strain for the as-cast alloy is 39.6%, reducing to 31.1% after solution heat treatment and water quenching. It again increases to 43.1% after aging.

Abstract