Effects of heat treatment on the microstructure and mechanical properties of AA2618 DC cast alloy

Effect of Zr Addition on Overaging and Tensile Behavior of 2618 Aluminum Alloy

“…The Cu-containing phases significantly evolved during solution heat treatment: no Al 2 Cu particles were observed after soaking at 525 • C, while only small phases containing Cu, Mg, and Ni were observed in the solution-treated samples (Figure 3). This is in agreement with existing literature data [24,25] Figure 3 shows the microstructure after solution treatment, consisting in soaking the alloys at 525 °C for 8 h. This treatment step was applied in order to bring the elements for precipitationhardening into solid solution, in this case Cu and Mg, which are present in primary coarse particles in the as-cast microstructure. Additionally, precipitation of nanosized Zr-based phases is also supposed to occur during this treatment stage.…”

“…Most of the intermetallic phases that were found (shown in Figure 2) are aluminide particles of AlxFeNi type. The Fe-Ni ratio, as observed by SEM-EDS analyses, is close to 1; the stoichiometry is therefore in good agreement to the well-known Al9FeNi formula proposed in literature [4,[24][25][26]. Fe-Ni intermetallics, hard and insoluble phases, limiting grain growth during solution treatment and high temperature working conditions, are known to induce a good thermal stability in 2618 alloy [4,5,26,27].…”

“…This should be ascribed to the fact that no precipitation of Zr-based primary phases occurred during solidification, thanks to the rapid cooling from the molten state obtained by permanent mold casting. Table 2 shows the chemical composition of the most common intermetallic particles found in as cast 2618 and 2618 + Zr; the corresponding suggested formula is proposed by comparing SEM-EDS results and existing literature data [5,24,25]. Most of the intermetallic phases that were found (shown in Figure 2) are aluminide particles of Al x FeNi type.…”

“…Table 3 summarizes the chemical composition of intermetallic particles observed in 2618 and 2618 + Zr after solution treatment. Due to their resistance to dissolution, even at temperatures as high as 600 • C [24], Al 9 FeNi particles are still present after solution treatment in both 2618 and 2618 + Zr, however, fragmented with respect to the as-cast condition as a result of the dissolution process. The Cu-containing phases significantly evolved during solution heat treatment: no Al 2 Cu particles were observed after soaking at 525 • C, while only small phases containing Cu, Mg, and Ni were observed in the solution-treated samples (Figure 3).…”

Mechanical Properties Analysis of Al2024 alloy Submitted to Different Aging Time and different Cold Plastic Deformation degree

“…SSS refers to supersaturated solid solution, GPB refers to Guinier-Preston-Bagaryatsky zones and S" and S' are the precursors of the equilibrium phase S (Al 2 CuMg). According to Elgallad et al 16 there is an emerging view that the differences between GPB, GPB2 and S" are insufficient to be firmly confirmed, and these three constituents are generally referred to as GPB zones.…”