Influence of the Solution and Artificial Aging Treatments on the Microstructure and Mechanical Properties of Die-Cast Al–Si–Mg Alloys

Abstract

Heat treatment is widely used to improve the properties of Al–Si–Mg alloys and its outcomes are influenced by the parameters applied during the treatment. This study describes the effect of the solution and artificial aging treatments on the microstructure and mechanical properties of die-cast Al–Si–Mg alloys. The microstructure of the as-cast Al–Si–Mg alloy was mainly composed of α-Al, complex needle-type eutectic Si particles, Mg2Si, and α-AlFeMn. The complex needle-type eutectic Si particles disintegrated into spheroidal morphologies, while the Mg2Si was dissolved due to the solid solution treatment. The maximum yield strength (YS) and ultimate tensile strength (UTS) values were 126.06 and 245.90 MPa at 520 °C after 90 min of solution heat treatment, respectively. Although the YS and UTS values of the Al–Si–Mg alloys reduced due to the solution treatment, the elongation (EL) of the solid solution heat-treated Al–Si–Mg alloys was improved in comparison to that of the as-cast Al–Si–Mg alloy. The maximum YS and UTS of 239.50 and 290.93 MPa were obtained after performing artificial aging at 180 °C for 180 min, respectively. However, the EL of the aging heat-treated alloy was reduced by a minimal value.

The Effect of Heat Treatment on the Mechanical Properties and Oxidation Resistance of AlSi10Mg Alloy

“…The formation of the β-Mg2Si phase reduces silicon concentration in molten solution. This prevents the growth of silicon particles and causes the formation of finer silicon particles [23][24][25][26][27]. There is no important change in the microstructure of the air-cooled Al-10Si-Mg alloy samples compared to the as-cast condition (Fig.…”

“…As the temperature decreases, the α(Al) phase begins to grow. As the chemical composition of the Al-10Si-Mg alloy approaches, the eutectic point, silicon, and magnesium react to form β-Mg 2 Si, and solidification is completed [26,27]. The formation of the β-Mg2Si phase reduces silicon concentration in molten solution.…”

“…The reason why the primary silicon particles in the quenched state of the Al-10Si-Mg alloy is higher than in the cast state of the alloy may be due to the growth of needle-shaped eutectic silicon particles during the dissolution and quenching process. The disappearance of the Mg 2 Si phase in the structure can be explained by the high diffusion rate of magnesium in the α(Al) phase [26,27]. During aging, Mg and Si atoms are withdrawn from solution, forming unstable fine Mg 2 Si precipitates [23][24][25][26][27].…”

“…There are numerous studies in the literature on the production of Al-10Si-Mg alloys. However, in these studies, the effect of process conditions on the microstructure and mechanical properties of the alloys was investigated [24][25][26][27]. Based on the literature studies, it was concluded that applying different heat treatments to the Al-10Si-Mg alloy did not fully reveal its friction and wear properties.…”

Aging and wear characteristics of A356 alloy with Er and Zr addition

“…It is noted that the mechanical properties of cast Al-Si-Mg alloys depend strongly on the dendrite arm spacing (DAS) [49] and the heat treatment conditions (SHT temperature/time and aging temperature/time) [50]. Besides, microstructural changes and the increase in the casting defects during heat treatment can negatively affect the mechanical properties [21].…”