MEASUREMENTS OF THE DRAGGING SMALL OXIDE PARTICLES OF MIGRATING GRAIN BOUNDARIES IN COPPER.
HARVARD UNIV CAMBRIDGE MASS DIV OF ENGINEERING AND APPLIED PHYSICS
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Grain boundaries, introduced into a copper single crystal by indenting and annealing the crystal, are shown to drag certain small 4000A diameter oxide particles with them when they migrate. GeO2 and B2O3 particles are dragged rapidly with speeds up to 1 micron per minute at temperatures between 650 and 1050C SiO2 particles are rather less mobile, and Al2O3 particles are, within the accuracy of the experiments, immobile. Measurements of the distance through which particles are dragged as a function of time and temperature yield activation energies for the dragging process, and mobilities for each sort of particle. Above 1000C, the mobile particles all show about the same activation, energy, and mobility all aspects of their movement suggest that their mobility is controlled by diffusion of matrix atoms in the interface between particle and matrix. At lower temperatures the mobilities and activation energies become strongly dependent on the composition of the particles, and cannot readily be explained. Author