Abstract
Superplasticity during temperature cycling of particle reinforced metal matrix composites has been studied over a range of reinforcement sizes and volume fractions. Above a critical volume and thermal cycle amplitude, the mean strain per cycle is proportional to stress and approximately proportional to cycle amplitude. For a given thermal cycle the constant of proportionality with respect to stress increases with reinforcement fraction to a maximum at around 30%; it then decreases with further increase in reinforcement. Transmission electron microscopy revealed no characteristics dislocation substructure; even after 90% strain the material was indistinguishable from its undeformed state. The experimental results confirm an internal plastic flow model for the phenomenon rather than an enhanced creep. A model of the process derived from the Lévy-Von Mises equations predicts both the effect of thermal cycle amplitude the MMC microstructure on the enhanced creep rate. © 1990.
| Original language | English |
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| Pages (from-to) | 2537-2552 |
| Number of pages | 15 |
| Journal | Acta Metallurgica (Online) |
| Volume | 38 |
| Issue number | 12 |
| Publication status | Published - Dec 1990 |