High-Strength, High-Conductivity, Two-Phase Materials

Abstract

<p>Heavily deformed, two-phase materials have been shown to exhibit strengths well in excess of the rule-of-mixtures prediction using the bulk properties of the constituents. The work described in this thesis investigates a number of aspects regarding high-strength, high-conductivity, two-phase materials. Microstructural observations and mechanical testing were used to examine the process of co-deformation, the evolution of mechanical properties, and the thermal stability of these heavily deformed structures. Materials selection procedures for the design of high-field magnet coils were developed.</p> <p>The sustained co-deformation of the two-phases leads to the conclusion that the second phase behaves as a shearable obstacle to dislocation motion. The increase in strength displayed by the two-phase material over the bulk constituent strengths may be explained by existing models of particle shearing if increased interfacial energy due to residual stress is accounted for. The increased work hardening displayed by copper-silver alloys subjected to intermediate annealing treatments is explained by a continuum description of the evolution of slip line length.</p> <p>The combination of materials selection procedures and investigations into the strengthening and resistive mechanisms have led to a new approach to the design of non-uniform composite materials to optimize strength and resistivity in two-phase materials.</p>