Application of crystal orientation mapping to local orientation perturbations

Crystal Orientation Mapping (COM) is a new state-of-the-art technique for m aking spatially specific orientation measurements based on the automatic an alysis of electron backscatter diffraction patterns. The main aim of the wo rk reported is to demonstrate the quantitative application of COM for chara cterising local orientation perturbations in the vicinity of triple junctio ns in an Al-3wt%Mg alloy deformed 5% in tension. First, the hardware config uration of the EBSD system is described and the optimum microscope operatin g conditions for setting up a COM are determined by measuring the spatial r esolution of EBSD patterns in pure Al and Ni specimens. For this particular investigation, an accelerating voltage of 20 kV was found to be optimum fo r mapping, resulting in spatial resolutions of 0.51 mu m and 0.42 mu m for Al and Ni respectively. Secondly, to provide a visual representation of loc al orientation perturbations in the vicinity of a triple junction, a COM an d pattern quality map are presented. The "raw" orientation data, extracted from the COM was quantified using several different post-processing methods . The methodology associated with each is discussed and comparisons of the pattern of orientation perturbations are made using the same "raw" data set .