| The design and fabrication of high-strength conductors is a challenging materials engineering problem which requires materials possessing very high strength and high electrical conductivity. As it is difficult to optimize both of these properties in one material, the solution is to design a composite material. There are many approaches which may be taken to designing high-strength composite conductors. In the present work, composites made of copper and austenitic stainless steel were fabricated and characterized.; The limiting factor in the performance of the copper-stainless steel composites examined is the strength of the stainless steel. In this context, a study was undertaken of the work hardening behaviour of austenitic stainless steel. This class of steels exhibits a strain-induced martensite transformation when deformed, which creates a two-phase material containing austenite and martensite. The effect of the martensite transformation on the work hardening behaviour of the stainless steel was studied.; In this thesis the approach taken was to study the mechanical properties of the austenite and the martensite phases individually, using a variety of techniques. The work hardening behaviour of the steel containing both phases was interpreted in terms of the individual properties of each phase, and is characterized by an extended elastoplastic transition. This was found to be responsible for a high rate of work hardening at very high strength levels.; The kinetics of the martensite transformation was studied, and the detailed structure of the transformation product. This information was used to model the kinetics of the transformation, and the resultant strengthening which occurs from the strain-induced martensite transformation. |
