Abstract
Recently, extensive studies have been carried out on the particle dispersion strengthened alloy in which particles are uniformly dispersed into matrix. Also, a successful development of FRP has been reported, and it is of great interest to study the composites containing fibers instead of particles. In this report, the results of the tensile test on the aluminum composite containing tungsten fibers (diameter=500 μ, 200 μ, 50 μ and 25 μ) and nichrome fibers (diameter=500 μ) are described. In any study of this nature, the preparation of specimens is a very important problem and one of the advantageous features of this report is that the specimens are prepared by foil metallurgy. The results obtained on these specimens are as follows:
(1) For the composites containing continuous fiber, the way of strengthening was found to be similar to that in many reports so far published. The value for the critical fiber volume percentage was 0.8% for the tungsten fiber and 0.5% for the nichrome fiber. Such a comparatively lower percentage was one of the characteristics of this type of composites.
(2) Considerable strengthening was also found on the composites containing discontinuous fibers. Various values were calculated from the experimental values. The values for the critical length of fibers were found to be unexpectedly longer, suggesting a more complicated strengthening mechanism. The strengthening factor for the discontinuous fiber κ is 0.22, 0.13 and 0.13 for the tungsten fiber with a diameter of 200 μ, 50 μ and 25 μ, respectively, and the value of κ in this case is κ=σf′⁄σf=1−lc⁄2l where σf=tensile strength of fiber, σf′=value of specific strengthening effect for discontinuous fiber, lc=critical length of fiber and l=length of fiber.
