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Micrograph 616 and full record

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Micrograph no
616
Brief description
Cavity formation in a tensile loaded alumina particulate composite
Keywords
alumina Link to MATTER Glossary entry for alumina, annealing Link to MATTER Glossary entry for annealing, cavity, composite material Link to MATTER Glossary entry for composite material, drawing Link to MATTER Glossary entry for drawing, extrusion Link to MATTER Glossary entry for extrusion, MMC, particle, reinforcement Link to MATTER Glossary entry for reinforcement, tensile
Categories
Composite
System
Al
Composition
Commercial purity (99.5%) + 15 micron angular alumina particles
Standard codes
Reaction
N/A
Processing
Al powder has been atomised and mixed with reinforcement particles. The mixture was tumbled for 12 hours, cold compacted (20MPa), extruded, annealed and then cold drawn (strain=1.64)
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
Technique
Scanning electron microscopy (SEM)
Length bar
80 μm
Further information
Horizontal stringers of fine oxide particles can be seen, parallel to the extrusion direction (horizontal). Under the tensile load, voids have nucleated at the interface between the matrix and the reinforcement particles, and some particle fracture has also occurred. Most voids form on planar faces normal to the tensile load (horizontal), and particularly where stringers of fine oxide particles also intersect the interface. These stringers provide interfacial flaws which may then be preferential sites for cavity nucleation.
Contributor
Prof T W Clyne
Organisation
Department of Materials Science and Metallurgy, University of Cambridge
Date
03/10/02
Licence for re-use
Attribution-NonCommercial-ShareAlike 4.0 International

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