Evolution of intermetallics, dispersoids and elevated-temperature properties at various Fe contents in Al-Mn-Mg 3004 alloys

Nowadays, great interests are rising on aluminum alloys for the applications at elevated temperature, driven by the automotive and aerospace industries requiring high strength, light weight and low cost engineering materials. As one of the most promising candidates, Al-Mn-Mg 3004 alloys have been found to possess considerably high mechanical properties and creep resistance at elevated temperature resulted from the precipitation of a large number of thermally stable dispersoids during heat treatment. In present work, the effect of Fe contents on the evolution of microstructure as well as high temperature properties of 3004 alloys has been investigated. Results show that the dominant intermetallic changes from α-Al(MnFe)Si at 0.1 wt. % Fe to Al6(MnFe) at both 0.3 and 0.6 wt. % Fe. In the Fe range of 0.1 to 0.6 wt. % studied, a significant improvement on mechanical properties at elevated temperature has been observed due to the precipitation of dispersoids, and the best combination of yield strength and creep resistance at 573K (300°C) is obtained in the 0.3% Fe alloy with finest size and highest volume fraction of dispersoids. The superior properties obtained at 573K (300°C) makes 3004 alloys more promising for high temperature applications. The relationship between the Fe content and the dispersoid precipitation as well as the materials properties has been discussed