The Nature of Slip in Aluminum Crystals Containing Hard Particles

摘要

The report discusses certain two phase alloys remarkable for being plastically nonhomogeneous: one component of the microstructure deforms freely but the other deforms by a smaller amount, or not at all. Laue patterns, measurements of shape change, measurements of asterism by a diffractometer technique, and electron microscopy give information about the nature of slip in such alloys. These techniques were used to study crystals of Al - 3% Cu, aged to give plates which are sufficiently strong to show effects expected of a plastically non-homogeneous alloy; similar measurements were made on identical, but unaged, crystals. The results show that the two phase crystal deformed predominantly by single slip, but that extremely large gradients of shear were present in it, leading to lattice rotation and thus asterism. The rotations vary over a wavelength equal to the particle spacing, so a large lattice curvature develops, and a large density of dislocations must be stored in the crystal to accommodate the curvature. (Author)