Microstructural behavior of rapidly solidified and extruded Al-14wt%Ni-14wt%Mm (Mm, misch metal) alloy powders

The effect of powder size on the microstructure and mechanical properties was studied in gas-atomized Al-14wt%Ni-14wt%Mm (Mm: misch metal) alloy powder and their extrudates. The alloy powders showed different microstructures depending on the powder size. With decreasing powder size, formation of intermetallic compounds such as Al3Ni, Al11Ce3 and Al11La3 was suppressed. The powders less than 26 μm in diameter consisted of nanocrystalline fcc-Al particles embedded in an amorphous matrix. Microstructural scale of the extruded bar decreased as the initial powder size was decreased. The ultimate tensile strength of the alloy bar has increased from about 512 to 728 MPa with decreasing initial powder size from 75 to 90 μm to −26 μm. The strength increase mainly results from structural refinement.