Comparison of Mechanical and Microstructural Properties of as-Cast Al-Cu-Mg-Ag Alloys: Room Temperature vs. High Temperature

Abstract

Unfolding the structure–property linkages between the mechanical performance and microstructural characteristics could be an attractive pathway to develop new single- and polycrystalline Al-based alloys to achieve ambitious high strength and fuel economy goals. A lot of polycrystalline as-cast Al-Cu-Mg-Ag alloy systems fabricated by conventional casting techniques have been reported to date. However, no one has reported a comparison of mechanical and microstructural properties that simultaneously incorporates the effects of both alloy chemistry and mechanical testing environments for the as-cast Al-Cu-Mg-Ag alloy systems. This preliminary prospective paper presents the examined experimental results of two alloys (denoted Alloy 1 and Alloy 2), with constant Cu content of ~3 wt.%, Cu/Mg ratios of 12.60 and 6.30, and a constant Ag of 0.65 wt.%, and correlates the synergistic comparison of mechanical properties at room and elevated temperatures. According to experimental results, the effect of the precipitation state and the mechanical properties showed strong dependence on the composition and testing environments for peak-aged, heat-treated specimens. In the room-temperature mechanical testing scenario, the higher Cu/Mg ratio alloy with Mg content of 0.23 wt.% (Alloy 1) possessed higher ultimate tensile strength when compared to the low Cu/Mg ratio with Mg content of 0.47 wt.% (Alloy 2). From phase constitution analysis, it is inferred that the increase in strength for Alloy 1 under room-temperature tensile testing is mainly ascribable to the small grain size and fine and uniform distribution of θ precipitates, which provided a barrier to slip by deaccelerating the dislocation movement in the room-temperature environment. Meanwhile, Alloy 2 showed significantly less degradation of mechanical strength under high-temperature tensile testing. Indeed, in most cases, low Cu/Mg ratios had a strong influence on the copious precipitation of thermally stable omega phase, which is known to be a major strengthening phase at elevated temperatures in the Al-Cu-Mg-Ag alloying system. Consequently, it is rationally suggested that in the high-temperature testing scenario, the improvement in mechanical and/or thermal stability in the case of the Alloy 2 specimen was mainly due to its compositional design.

Difference in the Precursory Process of the Intergranular Corrosion of Aged Al-Cu and Al-Cu-Mg Alloys in 0.1 M NaCl

“…The small Al 2 Cu in the grain boundaries was determined to be precipitated by artificial aging. 46,47 Fine precipitates caused by aging were also observed in the grains.…”

Effect of the Cu/Mg Ratio on Mechanical Properties and Corrosion Resistance of Wrought Al–Cu–Mg–Ag Alloy

“…The alloys were prepared from pure bulk elements melted at 730 °C and cast heated mold of steel at 450 °C. The resulting ingots were then homogenized at 520 °C 24 h, followed by furnace cooling [28]. The chemical composition of the ingots was lyzed using SPECTRO MAXx Spectral analyzer, and the results are shown in Table 1 The alloys were prepared from pure bulk elements melted at 730 • C and cast into heated mold of steel at 450 • C. The resulting ingots were then homogenized at 520 • C for 24 h, followed by furnace cooling [28].…”

“…The resulting ingots were then homogenized at 520 °C 24 h, followed by furnace cooling [28]. The chemical composition of the ingots was lyzed using SPECTRO MAXx Spectral analyzer, and the results are shown in Table 1 The alloys were prepared from pure bulk elements melted at 730 • C and cast into heated mold of steel at 450 • C. The resulting ingots were then homogenized at 520 • C for 24 h, followed by furnace cooling [28]. The chemical composition of the ingots was analyzed using SPECTRO MAXx Spectral analyzer, and the results are shown in Table 1.…”

“…These sheets were then solution-treated at 520 • C and quenched in water at room temperature, inducing the formation of a supersaturated solid solution (SSS). Afterwards, the samples were aged in a salt bath at 180 • C to determine the aging peak point for hardness [28,29], as shown in Figure 2. A hardness test, Vickers hardness type, was performed on the scale of 10 KgF during the 15 s. The hardness was determined by taking an average of 5 indents at a random location on the sample.…”

Sustainability through Optimal Compositional and Thermomechanical Design for the Al-7XXX Alloys: An ANOVA Case Study

“…In recent years, researchers have studied the properties and microstructure of Al-Zn-Mg-Cu alloys under various treatments due to their high strength-to-weight ratio, superior absorption capacity, good machinability, good corrosion resistance, and excellent weldability. The aforementioned characteristics of Al-7XXX alloys make them a good choice for designing and manufacturing critical structural components in aviation, space, and defense industries [1][2][3][4][5][6][7][8][9][10][11][12]. However, the ever-growing demand for industrial sustainability presents a significant challenge for material scientists to develop novel processing routes to improve the mechanical properties of these materials further while ensuring a sizeable manufacturing scale.…”