Structure and polygonization of bent zinc monocrystals

摘要: Abstract The geometry of bent zinc crystals is discussed. It found that the slip planes in have shape involutes with hexagonal axes lamellae parallel to tangents evolute. This concurs other investigators' results for corundum-crystals and theory. Evidence presented show crystals, especially sharply ones, are not necessarily polygonized immediately after bending. They sometimes contain low-angle grain-boundaries which may or form during bending process. normal structure a homogeneously crystal believed consist network meandering dislocation lines connecting short segments walls. Quantitative data on kinetics polygonization cylindrically presented. Polygonization, absence inhomogeneous stresses, does occur below about 170°C “chemicallypure” this temperature raised somewhat by contamination 0.1 at. % Cd. At given temperature, polygon angles increase proportion logarithm time. dependence growth rate, dθ/dt, at constant angle, varies temperature. If an Arrhenius equation used describe it temperatures 250°C, Q ~60 kcal/mol from 250 325°C, ~20 kcal/mol. effect several variables rate were investigated: 1. Stress annealing: causes boundaries coalesce. 2. Twins: compression side they markedly inhibit growth. 3. Bending temperature: variations −196°C 225°C had no marked effect. 4. Surface condition: as long surface was macroscopically smooth. 5. Intermittent versus continuous anneals: 6. Skew bending: small amounts skewness. 7. Radius curvature: size roughly inversely proportional radius curvature time theory discussed pointed out climb unit dislocations seem be only factor controls rate.