Hardening Behavior in Aged Al-4%Cu-0.3%Mg Alloys with 0.5 and 2%Ag Additions

Abstract

The precipitation characterization of Al-4 mass% Cu-0.3 mass% Mg alloy with additions of 0.5 and 2 mass% Ag during aging treatments was carried out by transmission electron microscopy (TEM) and microhardness measurements. TEM observation of aged samples showed that the phase is the dominant phase and it is in coexistence with the 0 phase. Additionally, the phase has the morphology of polygonal prism (almost hexagonal) with flat interfaces and a thin thickness. The variation of the cube of mean radius of precipitates, r 3 , followed a linear relationship, as predicted by the Lifshitz, Slyosov and Wagner (LSW) theory for diffusion-controlled coarsening in both alloys. The coarsening process of the phase was slower in the aged Al-4 mass% Cu-0.3 mass% Mg-2 mass% Ag alloy. The decrease in hardness seems to be related to the coarsening of the phase and the loss of coherency.

Effect of Minor Er Additions on the Microstructures and Mechanical Properties of Cast Al-Cu-Mg-Ag Alloys

“…In contrast, the Ω phase not only exhibits high strength and excellent resistance to coarsening, but also reduces the coherency misfit strain and provides relatively low energy for coherent boundaries at elevated temperature of 250 °C [ 6 , 7 , 8 ]. However, the coarsening rate of Ω phase accelerates when the temperature further increases to 300 °C, limiting the use of the Al-Cu-Mg-Ag alloy [ 9 , 10 ].…”

Microstructural Features and Mechanical Properties of Artificially Aged AA2024

“…Various studies were conducted on the understanding of the formation and role of these precipitates on hardness and strength of the aged Al-Cu-Mg alloys [15][16][17][18][19][20][21][22][23]. The literature shows that the hardening of the aged Al-Cu-Mg alloys depends upon the distribution and types of these precipitates in the matrix [15][16][17][18][19][20][21]. The formation of S -phase precipitates in Al-Cu-Mg alloys during the aging treatment is found to be more useful in increasing the hardness and strength of the alloy than the Q-phase precipitates [5,14].…”