Further Comments on Strengthening in Deformation Processed Composite Materials (DPCM).

摘要

Dislocation Densities: It is apparently necessary to again state that no predictions of the dislocation density were given in either of oru papers formulating a substructural model. Calculation of dislocation densities from substructurally based models is dependent on choice of the proportionality constant between strength and the root of the dislocation density as well as on the 'partitioning' of dislocations between the phases. Calibration against suitable data for single phase copper gives an approximate check on the proportionality constant and allowed us to obtain the order of magnitude estimate of dislocation density given. To the extent that Spitzing et al. are now in agreement that these dislocation densities are consistent in magnetude with experimental observations over a very large range of strains, the current discussion has not been wasted. We trust that their future publications will reflect this. Comparison between model and experimental results with respect to differences in dislocation density between composites and heavily drawn copper is also attempted. The model value of thirteen quoted from is, however, clearly labeled as an upper bound, taken at the highest strain available and entirely ignoring the potential contributions of the ultrafine filamentary phase. In contrast, the experimental value of 'less than two' is actually smaller than the scatter bars on the data quoted. This comparison seems, therefore, more likely to confuse than to clarify the issue. (JES)