Analysis of neutron diffraction spectra acquired [ital in situ] during stress-induced transformations in superelastic NiTi
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States)
- LANSCE/MST, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
Neutron diffraction spectra were obtained during various stages of a reversible stress-induced austenite to martensite phase transformation in superelastic NiTi. This was accomplished by neutron diffraction measurements on bulk polycrystalline NiTi samples simultaneously subjected to mechanical loading. Analysis of the data was carried out using individual lattice plane ([ital hkl]) reflections as well as by Rietveld refinement. In the Rietveld procedure, strains in austenite were described in terms of an isotropic ([ital hkl] independent) and an anisotropic ([ital hkl] dependent) component. At higher stresses, austenite lattice plane reflections exhibited nonlinear and dissimilar elastic responses which may be attributed to the transformation. The texture evolution is significant in both austenite and martensite phases during the transformation and two approaches were used to describe this evolving texture, i.e., an ellipsoidal model due to March[endash]Dollase and a generalized spherical-harmonic approach. The respective predictions of the phase fraction evolution as a function of applied stress were compared. A methodology is thus established to quantify the discrete phase strains, phase volume fractions, and texture during such transformations. [copyright] [ital 1999 American Institute of Physics.]
- OSTI ID:
- 6337570
- Journal Information:
- Journal of Applied Physics, Journal Name: Journal of Applied Physics Vol. 86:6; ISSN JAPIAU; ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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Phase fraction, texture and strain evolution in superelastic NiTi and NiTi-TiC composites investigated by neutron diffraction
Stress-induced martensitic transformations in NiTi and NiTi-TiC composites investigated by neutron diffraction
Related Subjects
360102* -- Metals & Alloys-- Structure & Phase Studies
665100 -- Nuclear Techniques in Condensed Matter Physics -- (1992-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ALLOYS
AUSTENITE
CARBON ADDITIONS
COHERENT SCATTERING
CRYSTALS
DIFFRACTION
ELASTICITY
IRON ALLOYS
MARTENSITE
MECHANICAL PROPERTIES
NEUTRON DIFFRACTION
NICKEL ALLOYS
PHASE TRANSFORMATIONS
POLYCRYSTALS
SCATTERING
SHAPE MEMORY EFFECT
STRESSES
TENSILE PROPERTIES
TEXTURE
TITANIUM ALLOYS