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Three-dimensional microscopy has become an increasingly popular materials characterization technique. This has resulted in a standardized processing scheme for most datasets. Such a scheme has motivated the development of a robust software package capable of performing each stage of post-acquisition processing and analysis. This software has been termed Materials Image Processing and Automated Reconstruction (MIPAR™). Developed in MATLAB™, but deployable as a standalone cross-platform executable, MIPAR™ leverages the power of MATLAB's matrix processing algorithms and offers a comprehensive graphical software solution to the multitude of 3D characterization problems. MIPAR™ consists of five modules, three of which (Image Processor, Batch Processor, and 3D Toolbox) are required for full 3D characterization. Each module is dedicated to different stages of 3D data processing: alignment, pre-processing, segmentation, visualization, and quantification. With regard to pre-processing, i.e., the raw-intensity-enhancement steps that aid subsequent segmentation, MIPAR's Image Processor module includes a host of contrast enhancement and noise reduction filters, one of which offers a unique solution to ion-milling-artifact reduction. In the area of segmentation, a methodology has been developed for the optimization of segmentation algorithm parameters, and graphically integrated into the Image Processor. Additionally, a 3D data structure and complementary user interface has been developed which permits the binary segmentation of complex, multi-phase microstructures. This structure has also permitted the integration of 3D EBSD data processing and visualization tools, along with support of additional algorithms for the fusion of multi-modal datasets. Finally, in the important field of quantification, MIPAR™ offers several direct 3D quantification tools across the global, feature-by-feature, and localized classes.

Non-conventional transformation pathways have been exploited to determine the degree of refinement of the microstructure of a metastable -Ti alloy. This has involved a set of heattreatments where samples, initially quenched to room temperature (RT) from above the  transus are slowly heated to 350°C, then isothermal annealed at 350°C for various times prior to upquenching to 600°C and again isothermally annealed at that temperature, followed by quenching to RT. Interrupted treatments have also been performed so that the factors influencing the development of the final microstructure could be determined. Microstructures have been characterized by scanning and transmission electron microscopy, and atom probe tomography. It has been found that a distribution of the  phase may be formed whose scale is intermediate between the "super refined" and "refined" versions observed in previous research. The results are consistent with precursory isothermal  precipitates playing an indirect role in the formation of the refined distribution of the  phase via a non-conventional transformation pathway.

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The objectives of this work were to characterise and understand the effects of circular magnetic arc deflection (arc stirring) on grain structure refinement of gas tungsten arc weld beads made in Inconel 690 substrates. Welds were made at various arc stirring frequencies (1?5-50 Hz), and microstructures were analysed using optical and electron backscattered diffraction microscopy. Optimum refinement of grain size occurred at a stirring frequency of ,7 Hz. Analysis of computational fluid flow, heat transfer and solidification model results suggested that grain detachment was the primary mechanism for grain refinement.

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The formation of a columnar grain structure in high chromium nickel based alloy welds can be associated with cracking and poor resolution for ultrasonic non-destructive examination. The objective of this research was to characterise the effects of circular magnetic arc deflection (arc stirring) on grain structure of gas tungsten arc weld overlays made on Inconel 690 substrates with 52M filler wire. Welds and weld overlays were made at various arc stirring frequencies, and microstructures were analysed using optical and electron backscattered diffraction microscopy. Significant refinement of grain size occurred at a stirring frequency of 7 Hz. Ultrasonic nondestructive examination confirmed 100% improvement in signal/noise ratio in weld overlays made with magnetic stirring.