抄録
The tensile stress-strain behavior of copper matrix composites reinforced with helical tungsten fiber has been investigated using monofilamentary composite specimens. A tungsten fiber of 150μm in diameter was formed into a helix, whose helical angle was 78.4° and helical radius was 75μm. It was incorporated into copper matrix by means of electrodeposition. The volume fraction of fiber (Vf) studied ranged from 0.01 to 0.12. The composite specimens were tensiletested and the relations of stress with strain and Vf, the relations of recovery and permanent components in the total tensile strain, were examined. These results were compared with those on straight fiber reinforced composites. At the beginning of tensile deformation the flow stress of the helical fiber composite was smaller than that of the straight fiber composite at the same Vf. However, as the strain was increased, the flow stress of the helical fiber composite approached that of the straight fiber composite. The ultimate tensile stresses of the both kinds of composites at the same Vf were shown to be nearly equal. The flow stress of helical fiber composites were always larger than the values calculated by the rule of mixtures, while those of straight fiber composites well obeyed the rule. This phenomenon was considered to be due to the different deformation behavior of the helical fiber in the matrix as compared with the bare one and strong interaction between the helical fiber and the matrix during the early stage of deformation. The fracture strain decreased with increasing f for the both kinds of com-posites. However, significantly larger fracture strains were always observed for the helical fiber composites than for the straight fiber ones at the same f.
