Plastic deformation in polycrystalline materials involves a complex interaction of dislocations with defects in the lattice. The geometrically necessary component of the dislocation density can be quantified to some extent using data obtained from automated electron backscatter diffraction scans over planar regions or volumes using the three-dimensional imaging techniques that are currently available. Reliable measurements require that the step size of the orientation data used in determination of geometrically necessary dislocation densities be on the scale of the microstructural information. Measurements were performed in deformed Cu, Al and steel specimens. Geometrically necessary dislocation density in Cu deformed 10% in compression was about 15–30% of the overall estimated dislocation density. Measurements in Al demonstrate that three-dimensional estimates are on the order of 1.2–2 times the values obtained from 2D measurements on the same structures. Analysis of interstitial free steel specimens shows an increase in average geometrically necessary dislocation density by an order of magnitude for specimens deformed to 12% tensile deformation elongation.

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Stress corrosion cracking (SCC) is an established form of environmental attack in low karatage gold jewelry alloys. The cause of failure is often attributed to exposure to chlorinated solutions. At a certain gold content (usually greater than 14K) the alloy is widely believed protected from SCC. In this study, three commercial 18K gold alloys (yellow gold, nickel white gold, and palladium white gold) were tested in combination with three different household solutions to determine relative corrosion rates. These rates were determined using polarization tests. Once the maximum corrosion rate had been established, SCC tests using the constant potential dead weight method were used to determine time to failure. The resultant failure surfaces were examined to determine mode of fracture, which in all cases was predominantly intergranular. It was found that corrosion rates depended upon both the alloy system and the test solution. SCC was clearly demonstrated in 18K gold alloys, although in all cases times to failure were significantly greater than has been reported for lower karatage alloys. Palladium white gold was far more resistant to SCC than the other systems studied.