CORE-Materials
Section of a metal matrix composite (MMC) after extrusion and annealing
DoITPoMS, University of Cambridge
Commercial purity aluminium has atomised, mixed with 13 micron spherical alumina particles, ball milled, tumbled, cold compacted (20MPa) and then extruded (with the working direction vertical in the image). It has then been annealed at 630 degrees C. Vertical stringers of fine oxide particles are visible. Note the small yellow 'island' grain which has formed within one of the recrystallised grains and is likely to have nucleated on the adjacent reinforcement particle. Note also the boundary facets of some grains. These indicate a preferred habit plane and are probably coincidence site lattice (CSL) boundaries.
System
Al
Composition
Commercial purity (99.5%) + 13 micron alumina spheroids
Reaction
N/A
Processing
Commercial purity (99.5%) aluminium has been atomised, thoroughly mixed with alumina reinforcement particles and then extruded.
Applications
Metal matrix composites (MMCs) offer high specific stiffness which can be retained to high temperatures. This makes them suitable for applications in the aerospace industry. They also offer controlled (or zero) thermal expansion coefficients, good wear resistance and good impact properties.
Sample preparation
The sample has been oxidised to provide colour contrast for different grain orientations.
Technique
Reflected light microscopy, polarised
Contributor
Prof T W Clyne
Organisation
Department of Materials Science and Metallurgy, University of Cambridge
Section of a metal matrix composite (MMC) after extrusion and annealing
DoITPoMS, University of Cambridge
Commercial purity aluminium has atomised, mixed with 13 micron spherical alumina particles, ball milled, tumbled, cold compacted (20MPa) and then extruded (with the working direction vertical in the image). It has then been annealed at 630 degrees C. Vertical stringers of fine oxide particles are visible. Note the small yellow 'island' grain which has formed within one of the recrystallised grains and is likely to have nucleated on the adjacent reinforcement particle. Note also the boundary facets of some grains. These indicate a preferred habit plane and are probably coincidence site lattice (CSL) boundaries.
System
Al
Composition
Commercial purity (99.5%) + 13 micron alumina spheroids
Reaction
N/A
Processing
Commercial purity (99.5%) aluminium has been atomised, thoroughly mixed with alumina reinforcement particles and then extruded.
Applications
Metal matrix composites (MMCs) offer high specific stiffness which can be retained to high temperatures. This makes them suitable for applications in the aerospace industry. They also offer controlled (or zero) thermal expansion coefficients, good wear resistance and good impact properties.
Sample preparation
The sample has been oxidised to provide colour contrast for different grain orientations.
Technique
Reflected light microscopy, polarised
Contributor
Prof T W Clyne
Organisation
Department of Materials Science and Metallurgy, University of Cambridge