On the work hardening of fiber reinforced copper
- Massachusetts Inst. of Tech., Cambridge, MA (United States). Dept. of Materials Science and Engineering
- Risoe National Lab., Roskilde (Denmark). Materials Dept.
The prediction and optimization of metal matrix composite mechanical behavior necessitates an understanding of the influence exerted by the reinforcement on matrix plastic deformation. This influence can be substantial, as was first eloquently shown in 1969 by Kelly and Lilholt. In this work, composites of continuous 10 and 20 {micro}m diameter tungsten fiber reinforced copper composites were produced and tested in tension along the fiber direction. This system was chosen for its simplicity, both in structure and in processing: copper and tungsten feature no mutual solubility nor intermetallic phases, and copper wets tungsten well. The composites were fabricated by spontaneous infiltration of molten copper into packed bundles of parallel fibers held within cylindrical molds, followed by directional solidification to ensure proper feeding of metal solidification shrinkage. Resulting composites were free of pores, and their matrix was found to be essentially monocrystalline. In processing the composites, the fiber volume fraction V{sub f} was carefully measured by counting the number of fibers in each preform, checking that the fiber diameter was in good agreement (within 1%) with the nominal fiber diameter. V{sub f} values thus determined were also verified using measurements of composite density, to find good agreement; quoted V{sub f} values can thus be deemed reliable. The aim of the present note is to propose an alternative explanation for the Stage II matrix hardening rates measured in infiltrated copper-tungsten composites. The explanation is close to the original interpretation, but proposes an observable physical basis for the occurrence of plastically non-yielding matrix regions in Stage II.
- OSTI ID:
- 619464
- Journal Information:
- Scripta Materialia, Vol. 38, Issue 7; Other Information: PBD: 3 Mar 1998
- Country of Publication:
- United States
- Language:
- English
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