| Title |
Research Paper / Mechanical Behavior : Microstructural Stability and Strengthening Mechanism of Cu - 15Nb Filamentary Microcomposites : (2) Strengthening Mechanism |
| Authors |
안장호(Jang Ho Ahn); 홍순익(Sun Ig Hong) |
| Abstract |
In this study, the deformation and fracture behavior of the Cu-Nb microcomposites fabricated by the bundling and drawing process was investigated. The yield strength of a Cu-20% Nb microcomposite was predicted by modifying the model of Verhoeven et al. It was assumed that the substructural strengthening in pure Cu and Nb phase fully contribute to the yield strength of Cu-Nb microcompoaite, σ_(Cu-Nb), at low draw strains (η $lt; 5.5). At high drawing strains (η $gt; 5.5) where the microstructural scale of the Cu matrix is limited by Nb filaments, the contribution of the partial grain boundaries (connecting the edge of Nb filaments) to the strength was assumed to be proportional to (λ/W_(Nb))^½ The good agreement between the yield stress predicted in this study and the experimental data at drawing strains between 6 and 9.5 supports the suggestion of the present study that the effectiveness of substructure strengthening of Cu and Nb in heavily deformed Cu-Nb microcomposites is much lower than that expected from the yield strength of heavily deformed Cu and Nb. The yield stress of the Cu-Nb microcomposite fabricated by the bundling and drawing process was found to be in good agreement with the predicted yield stress of the present model. At drawing strains above 10, Nb filaments reached a thickness of approximately 10 ㎚ and there after further working resulted in random rupture of the filaments rather than continued plastic deformation and thinning, which may result in the slower increase of the strength than the predicted values with drawing strain. |