Oxidation of Manganese-Containing Aluminum Alloys Studied by SEM

Abstract

During remelting of aluminum manganese-containing alloys, some industrial experience has indicateda tendency toward increased oxidation losses when compared to unalloyed Al. A goal of thiswork is to increase current knowledge of oxidation of Mn-containing aluminum. An oxidation studywas performed on 99.99% Al, Al-1%Mn and Al-5%Mn materials in a muffle furnace in air. Theseoxidized materials were analyzed in the Scanning Electron Microscope using Energy Dispersive xraySpectroscopy (EDS) both for chemical composition and to analyze the structure of the oxide thatwas formed. The main findings from the SEM analysis of the oxidized 99.99% Al, Al1%Mn andAl5%Mn materials are: 1) The oxides formed on the Al1Mn and Al5Mn materials contained onlyminute amounts of Mn. However, small clusters of Mn metal were found among the Al2O3 particleson the surface of the Al1Mn and Al5Mn samples. 2) Dissolved Mn increased from the surface to theinterior, and Mn-rich particles were present in the interior of the Al1Mn and Al5Mn samples. 3) Theoxide layer thickness increases with Mn content, and the oxide film is more fragmented.