Materials science and engineering a-structural materials properties microstructure and processing vol:157 issue:1 pages:79-88
The mechanical alloying process has been applied to a blend of Al, Fe and Mn powders, in order to produce an Al alloy stabilized by inert dispersions and strengthened by a high volume fraction of intermetallics. The microstructure obtained after a first grinding operation consists of unreacted Fe and Mn particles embedded in a fine grained Al matrix. Intermetallics are formed during heat treatment of the milled powders and are refined in a subsequent mechanical alloying stage. During heat treatment of the powders a metastable Al6Fe intermetallic phase is formed. This phase is stabilized by Mn replacing part of the Fe which results in an Al6(Fe,Mn) intermetallic. In the alloy studied in detail (Al-5wt.%Fe-4wt%Mn), the intermetallic has the composition Al12FeMn. Some Al6Mn also forms around large Mn particles, slowing down diffusion of Mn towards the Al6Fe particles. Mechanical properties are evaluated and the E modulus is shown to be a function of the volume fraction of intermetallics.