The grain boundary character distributions in cast, recrystallized and strain annealed Ni3Al alloys with a composition of Ni23Al were examined to clarify the relation between ductility and the grain boundary character distributions in Ni3Al. The percentages of CSL boundaries in cast, recrystallized and strain annealed Ni3Al alloys are 26.8, 43.1 and 58.4%, respectively, of the total number of boundaries examined. The sum of the percentages for LAB (Low Angle Boundary) and Σ3 boundary in cast, recrystallized and strain annealed Ni3Al alloys is 4.46, 10.8 and 29.2% respectively. This indicates that strain annealing is effective in enhancing the frequency of occurrence of CSL boundaries, especially LAB and Σ3 boundary, in Ni3Al. The strain annealed Ni3Al alloy having a much higher frequency of CSL boundaries is found to exhibit elongation to fracture of more than 45%. This significant increase in elongation of the strain annealed Ni3Al alloys is attributed to the presence of relatively low energy LAB and Σ3 boundaries.
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