title: A procedure to create isoconcentration surfaces in low-chemical-partitioning, high-solute alloys.
abstract: A proximity histogram or proxigram is the prevailing technique of calculating 3D composition profiles of a second phase in atom probe tomography. The second phase in the reconstruction is delineated by creating an isoconcentration surface, i.e. the precipitate-matrix interface. The 3D composition profile is then calculated with respect to this user-defined isoconcentration surface. Hence, the selection of the correct isoconcentration surface is critical. In general, the preliminary selection of an isoconcentration value is guided by the visual observation of a chemically partitioned second phase. However, in low-chemical -partitioning systems, such a visual guide is absent. The lack of a priori composition information of the precipitate phase may further confound the issue. This paper presents a methodology of selecting an appropriate elemental species and subsequently obtaining an isoconcentration value to create an accurate isoconcentration surface that will act as the precipitate-matrix interface. We use the H-phase precipitate in the Ni-Ti-Hf shape memory alloy as our case study to illustrate the procedure.
authors: The University of Alabama, Department of Metallurgical and Materials Engineering, Tuscaloosa, AL, 35487 USA.
authors: B C
authors: BC
authors: Hornbuckle
authors: The University of Alabama, Department of Metallurgical and Materials Engineering, Tuscaloosa, AL, 35487 USA.
authors: M
authors: M
authors: Kapoor
authors: The University of Alabama, Department of Metallurgical and Materials Engineering, Tuscaloosa, AL, 35487 USA. Electronic address: gthompson@eng.ua.edu.
authors: G B
authors: GB
authors: Thompson
keywords: H-phase; High-solute; Isoconcentration surface; Low-chemical-partitioning; Proximity histogram