Metal matrix composites reinforced by gas-atomized Al-Cu-Fe powders

An Al₆₂Cu₂₆Fe₁₂ alloy was gas-atomized to prepare powders containing icosahedral quasicrystalline phase. For synthesizing composites, pure Al was selected as matrix material, and the Al₆₂Cu₂₆Fe₁₂ powders were added to the molten aluminum during the casting. A Ni coating with a thickness of approximately 5 μm deposited onto the Al₆₂Cu₂₆Fe₁₂ particles proved to be effective in preserving the original powder structure during casting. The composites showed a relatively good bonding between the Al₆₂Cu₂₆Fe₁₂ particles and matrix, despite the partial dissolution of the small satellite particles. Mechanical properties evaluated through compression and indentation tests of the composites indicated a significant increase of the yield stress especially in the range up to 10% volume fraction of reinforcing particles. Strengthening mechanisms were reviewed to estimate the role of the icosahedral and coexisting crystalline phases on the increase of the yield stress.