| This thesis reports an investigation involving a thorough examination of the effects of thermomechanical processing commercially pure nickel on the grain boundary character distribution. Successive cold working of low strain levels and annealing steps were used to increase the fraction of special coincident site lattice (CSL) gain boundaries, 3 ≤ Sigma ≤ 29. Low CSL boundaries were found consist of mostly twin (Sigma3) and twin related (Sigma3n) grain boundaries. Samples strained at less than or equal to 12% strain, one step or sequential steps, annealed between 500°C and 800°C for 10 minutes did not show improvement in special boundaries fraction compared to the as-received material with Sigmasp = 36.5%. Following the same sequence of strains, samples annealed at 1000°C for 10 minutes showed increases of special boundaries up to an average of Sigma sp ∼55%, but an excessive grain growth was seen for all the samples annealed at 1000°C. (Abstract shortened by UMI.)... |
