Nonbasal Glide in Dislocation-Free Cadmium Crystals. I. The (101̄1) [12̄10] System

Abstract

Electron‐transparent dislocation‐free platelets of cadmium were deformed in tension parallel to the basal plane, inside an electron microscope, in the temperature range from +25° to −150°C. At high strain rates the crystals twinned. At low strain rates (≲10⁻² sec⁻¹) the glide system depended on α, the angle between the tensile axis and a close‐packing direction. For 0≤α≲20° pyramidal glide on the (112̄2) [1̄1̄23] system occurred. For 20°≲α≤30° a new glide system, (101̄1) [12̄10], was identified which has not yet been observed in large cadmium crystals. Edge dislocations with a ⅓[12̄10] Burgers vector moved across the entire crystal on (101̄1) planes without multiplying or forming obstacles to further glide. Occasionally, at high strain, fracture occurred on a (101̄1) plane. The observations suggested that, in the temperature range studied, the flow stress for (101̄1) [12̄10] glide was considerably lower than that for prismatic glide on the (101̄0) [12̄10] system, slightly higher than that for (112̄2) [1̄1̄23] glide, and independent of strain for a given temperature.