Composite Materials for High-Temperature Magnetic Applications

Abstract

Different types of composite materials containing dispersoids, fibers, or aligned-eutectic structure in a matrix of either cobalt or iron or their alloys were investigated for potential use as solid-rotor core materials operating at 1200 to 1600 F under stress. Composite-strengthening methods deteriorated the soft-magnetic quality of the matrix material. Magnetic saturation induction (Bs) decreased in direct proportion to the volume fraction of nonmagnetic phase present. In regard to structure-sensitive magnetic properties, such as coercive force (Hc) and d-c magnetization curve, the effects of matrix composition, amount and distribution of secondary phase, internal stress, demagnetization effects, and temperature were studied experimentally and interpreted by reference to theory. The overall consideration of both magnetic and mechanical performance, as well as ease of processing and thermal stability, favored dispersion-strengthened iron + 27 weight percent cobalt-base material for further development.