Microstructures and strengthening mechanisms of high Fe containing Al–Mg–Si–Mn–Fe alloys with Mg, Si and Mn modified

Abstract

In this paper, two high Fe containing Al–Mg–Si–Mn–Fe alloys with Mg, Si and Mn modified were prepared, and their microstructures and mechanical properties were comparatively studied with a common applied alloy. Furthermore, the effects of alloying elements on their microstructures and the corresponding strengthening mechanisms were analyzed. It was found that the two Al–Mg–Si–Mn–Fe alloys exhibited good combination of strength and elongation in spite of their high Fe content. When compared with the common applied alloy, the yield strength of the two alloys was increased by 28 MPa and 50 MPa respectively, whereas the elongation was only slightly decreased. The higher strength of the two Al–Mg–Si–Mn–Fe alloys was mainly attributed to precipitation and solid solution strengthening which were substantially caused by the appropriated proportion of Mg and Si. Owing to the appropriate addition of Mn, no β–AlFeSi phases were found in the alloys, and the detriments of Fe were fully eliminated. The submicron scaled α–Al(FeMn)Si phases slightly improved the yield strength because of their contribution to grain refinement and dispersion strengthening. The results of this paper provide a valuable insight into the strengthening and industrial manufacturing of Al–Mg–Si alloys.