Uncovering the origin of enhanced strengthening in Li-added Al–Cu–Mg alloys

Effect of Microstructure on High Cycle Fatigue Behavior of 211Z.X-T6 Aluminum Alloy

“…The histogram of the size distribution of coarse second phase or inclusion is depicted in Figure 16, and the relationship between the grain size of the second phase and the strength of the alloy is illustrated in Figure 17. The precipitated phase size and grain size followed the same trend without considering the difference between the two microstructures of 211Z.X alloy (Figures [15][16][17]. In other words, the increase in grain size led to the growth of long and short diameters of the second phase (Figure 15).…”

“…The main alloy elements Cu, Mg, Mn, and Zn have certain strengthening effects on aluminum alloys, but their main role is to improve the heat and corrosion resistances of the material [8,13,14]. Furthermore, small numbers of auxiliary elements, such as Ni, Ti, Cr, Zr, and B, exist in alloys, which can further improve their properties [13][14][15][16][17][18]. However, the Fe and Si elements are harmful impurity elements for aluminum alloys with high strength and should be avoided as much as possible [7,19].…”

Effect of lithium on mechanical and corrosion properties of friction stir back extruded Al-Cu-Mg alloy

“…4 and Table 1. According to the results of EDS analysis and composition of precipitates and secondary phase particles reported by other researchers [19], the microstructure of the alloys in the as-cast state mainly includes Fe-rich particles, eutectic structure, and Cu-Mg-rich precipitates. Meanwhile, in the samples containing lithium, a little lithium can also be seen in the Cu-Mg-rich precipitates.…”

“…In this research, Al-Cu-Mg alloy with the copper to magnesium ratio of 3.8 has been selected as the base alloy, and the lithium element has been added to the base alloy as a micro-alloy in amounts less than 0.5 wt.%. The reason for adding lithium in amounts less than 0.5 wt.% is based on [19], where it is mentioned that in amounts less than 0.5 wt.%, it is not possible to form complex compounds and precipitates in the microstructure, and the added lithium will lead to the acceleration of the formation of S-Al 2 CuMg precipitates. To manufacture the cast alloys, commer- cial AA2024 with a chemical composition of 0.18 % Si, 3.98 % Cu, 1.04 % Mg, 0.24 % Fe, 0.51 % Mn, and Al balance (wt.%) was melted in an electric resistance furnace.…”

“…In addition to the studies conducted on Al-Li alloys which are mainly strengthened by the T1 phase and δ phase [12,13], various studies [14][15][16][17][18] have also been conducted to investigate the effect of lithium on Al-Zn-Mg and Al-Cu-Mg based alloys and show that the addition of partial lithium can significantly affect the precipitation behavior of Al alloys. Duan et al [19] investigated the effect of adding a small amount of lithium to an Al-Cu-Mg alloy. They reported that the addition of 0.5 wt.% of lithium resulted in a significant improvement in tensile strength without significant loss in ductility.…”