APT Presentation - George J. Ferko V

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Slide 1Atomic Probe Tomography Proposed ExperimentGeorge J. Ferko V9/27/121Hypothesis and Introduction9/27/12Disspute over existence of type-III complexions APT solution3D mapping of GB volumeSub-nanometer spatial resolutionMeasure Gibbsian GB solute excess2Defense of Hypothesis9/27/12Major issues with APTDifficulty of sample prepNo direct observation of GB widthDetermining GB widthCalculated from Gibbsian excess from the concentration profileNumber of mono-layers is expected to be ~2Letellier, L, et al., Direct Observation of Boron Segregation at Grain-Boundaries in Astroloy by Atomic Tomography, Scripta Metallurgica et Materialia, 30, 1994, pp. 1503-1508, and Hudson, D and G. Smith, Initial Observation of Grain Boundary Solute Segregation in a Zirconium Alloy (ZIRLO) by Three-Dimensional Atom Probe, Scripta Materialia, 61, 2009, pp. 411-414.3Critical Experiment9/27/12Dillon, SJ, and Harmer, MP, Multiple grain boundary transitions in ceramics: A case study of alumina, Acta Materialia, 55, 2007, pp. 5247-5254.Miller, MK, et al., Review of Atom Probe FIB-Based Specimen Preparation Methods, Microscopy and Microanalysis, 13, 2007, pp. 428-436.Thompson, K, et al., Three-dimensional Atom Mapping of Dopants in Si Nanostructures, Applied Physics Letters, 87, 2005, pp. 052108-1-3.FIB lift outWelding area of interest to microtipAnnular millingSpecimen requirementsTip radius ~50 to ~150 nmSide taper < 5Low current/low accelerating voltage used in final steps4Critical Experiment (cont.)9/27/12Miller, MK, et al., Review of Atom Probe FIB-Based Specimen Preparation Methods, Microscopy and Microanalysis, 13, 2007, pp. 428-436.Moody, MP, et al., Qualification of the Tomographic Reconstruction in Atom Probe by Advanced Spatial Distribution Map Techniques, Ultramicroscopy, 109, 2009, pp. 816 Miller, MK and RG Forbes, Atom Probe Tomography, Materials Characterization, 60, 2009, pp. 462Seidman, DN, and K Stiller, An Atom-Probe Tomography Primer, MRS Bulletin, 34, 2009, pp. 719.Ga Implantation ProblemVoltage and laser pulses for ceramicsIons projected through local electrodeCrossed delay line detectorTime-of-flight detector5Interpretation of Results9/27/12Miller, MK and RG Forbes, Atom Probe Tomography, Materials Characterization, 60, 2009, pp. 465-466.Further insight into solute concentration profileIsoconcentration surfaces/volumesCalculation of Gibbsian excess will lead to the GB width3D reconstruction needs no interpretation if of good quality6