Speaker
Description
To extend the applicability of synchrotron diffraction contrast tomography (DCT) towards more plastically deformed materials, we have developed a forward-model based reconstruction method to reconstruct grain shapes and local orientations in materials exhibiting levels of intragranular orientation spread that can no longer be handled with the conventional Friedel pair based indexing and tomographic reconstruction approach. This method consists of seed and regional indexing, in which an exhaustive searching and fitting of orientations is first performed to index the seed orientation and then a regional indexing by testing a list of local orientations around the seed orientation is carried out to maximize the completeness. The capability of this novel method was benchmarked and compared with the reconstructions based on the conventional Friedel pair matching and tomographic reconstruction method using samples made from fully recrystallized Al-Cu alloy, moderately deformed α-Ti alloy and 10% creep ruptured Fe-Au alloy. The results show that this method has a great prospect in overcoming the deformation constraint and can reconstruct reasonably well the intragranular orientations. It is also suitable for multi-phase reconstruction and both box-beam and line-beam acquisition geometries. The implementation has been made flexible supporting the use of single or multiple GPU machines. The strengths and weaknesses of the current forward-model based reconstruction have been discussed in detail with respect to the conventional Friedel pair matching method. To fully exploit and complement the strengths of the two methods, the code to implement the current forward-model based reconstruction has been fully integrated with the existing DCT code and is open sourced for beamline data processing.
