Development of Al–Mn–Mg 3004 alloy for applications at elevated temperature via dispersoid strengthening

Abstract

In this study, the potential applications of Al-Mn-Mg 3004 alloy at elevated temperature have been evaluated through the systematic study of the precipitation behavior of α-Al(MnFe)Si dispersoids and their effect on material properties during precipitation treatment and long-term thermal holding. The results demonstrate a significant dispersion strengthening effect caused by the precipitation of fine uniformly distributed dispersoids during precipitation treatment. The peak compression yield strength (YS) at 300°C of the experimental 3004 alloy can reach as high as 78 MPa due to a large volume fraction (~2.95 vol. %) of α-Al(MnFe)Si dispersoids. The dispersoids are found to be thermally stable at 300°C for up to 1000 h of holding, leading to consistently high mechanical performance and creep resistance. The superior and stable YS and creep resistance at 300°C enables the 3004 alloy to be applied to weight-sensitive applications at elevated temperatures.

The Influence of Cu Addition on Dispersoid Formation and Mechanical Properties of Al-Mn-Mg 3004 Alloy

“…A trace of Cu was detected in the dispersoids in the Cu containing alloys by TEM-EDS analysis. All dispersoids are identified as α-Al(Mn,Fe)Si according to the results of TEM-EDS and literature [1][2][3]5,6]. The equivalent diameter of the dispersoids in the base alloy (DU0) is 47 nm, whereas the diameters of the dispersoids in the Cu containing alloys are between 32 and 37 nm (Figure 7a), which is smaller than that in the base alloy.…”

“…In the base alloy (DU0, Cu-free), two types of intermetallic particles were observed (Figure 2a). The grey particles correspond to the Al 6 (Mn,Fe) intermetallic phase and the black ones are primary Mg 2 Si [6,9,13]; both are intermetalllics distributed in the interdendrite regions. In the Cu containing alloys, the grey particles are Al 6 (Mn,Fe) intermetallic, in which a small amount of Cu can be detected.…”

“…The microstructure of the alloy containing 1.2% Cu is shown in Figure 2b. Using image analysis, the volume fractions of intermetallics as a function of Cu content were evaluated (Figure 3 α-Al(Mn,Fe)Si dispersoids can precipitate at approximately 400 °C during heat treatment in 3xxx alloys [3,6,7]. Figure 4 shows the optical images of DU0 and DU120 alloys after heat treatment at 425 °C for 6 h. The light yellow regions are the dispersoid zones where most of the dispersoids are concentrated and they are located inside the dendrite cells.…”

“…Recently, the strengthening effect of α-Al(Mn,Fe)Si dispersoids at ambient and elevated temperatures has been reported [1,[6][7][8]. Moreover, the α-Al(Mn,Fe)Si dispersoids have been proven to be thermally stable at 300 • C [6], which is especially attractive to materials for elevated temperature applications.…”

Evolution of Elevated-Temperature Strength and Creep Resistance during Multi-Step Heat Treatments in Al-Mn-Mg Alloy

“…It is reported that the yield strength of 3003 at room temperature (RT) after 375°C/24h has been improved to 80 MPa compared with 52MPa after 600°C/24h due to precipitation of dispersoids [7]. Recently, present authors have systematically studied the evolution of dispersoids at relative lower heat treatment temperature (300-425°C) and their influence on elevated-temperature properties in AlMn-Mg 3004 alloys [6,[8][9][10][11][12]. It is found that high volume fraction and well distributed α-Al(MnFe)Si dispersoids are observed after treated at 375°C for 48h, leading to the remarkable improved YS and creep resistance at elevated-temperature.…”