Three-dimensional in situ characterization of phase transformation induced austenite grain refinement in nickel-titanium. (15th March 2019)

• Record Type: Journal Article
• Authors: Bucsek, A.N.; Casalena, L.; Pagan, D.C.; Paul, P.P.; Chumlyakov, Y.; Mills, M.J.; Stebner, A.P.
• Is Part Of: Scripta materialia. Number 162(2019)
• Page Start: 361
• Page End: 366
• Publication Date: 2019-03-15
• Subjects: Shape memory alloys -- Coincident lattice -- Grain refining -- X-ray diffraction -- 3D reconstruction; Materials -- Periodicals; Metallurgy -- Periodicals; Metalen; Legeringen; Materiaalkunde; Metals, metalworking and machinery industries; Metals; Electronic journals; 620.11
• DOI: 10.1016/j.scriptamat.2018.11.043
• Languages: English
• ISSNs: 1359-6462

Abstract

Abstract: Near-field and far-field high-energy diffraction microscopy and microcomputed tomography X-ray techniques were used to study a bulk single crystal nickel‑titanium shape memory alloy sample subjected to thermal cycling under a constant applied load. Three-dimensional in situ reconstructions of the austenite microstructure are presented, including the structure and distribution of emergent grain boundaries. After 1 cycle, the subgrain structure is significantly refined, and heterogeneous Σ3 and Σ9 grain boundaries emerge. The low volume and uneven dispersion of the emergent Σ boundaries across the volume show why previous transmission electron microscopy investigations of Σ grain boundary formation were inconsistent. Graphical abstract: Unlabelled Image