RAPIDLY SOLIDIFIED ALUMINUM-IRON-MISCH METAL-ALLOYS

Three alloys with compositions of Al-10 Fe-1. 25 MM (misch metal), Al-6. 7 Fe-3. 2 MM and Al-3. 7 Fe-1. 2 MM were rapidly solidified into strips. Four broad categories of as-cast microstructures could be identified in all microstructures with the volume fraction of a microstructure being dependent on the composition and thickness of the strip. Similarly, the amount of Al//3Fe, Al//6Fe, and Al//8CeFe//4 intermetallics also varied with composition in the as-cast condition. Lattice parameter measurement by X-ray diffraction indicated that the opposing influence of iron and atoms such as cerium keeps the distortion in the aluminium lattice to below 0. 15% over that of pure aluminium. Heat treatment of the stips was carried out for temperatures up to 618 K and times up to 318 h to follow the changes occurring in the microstructure. These changes include coarsening of cells, precipitation and growth of intermetallics and cyclic changes in the measured microhardness values at different thickness locations in the strips.