Mapping of Texture and Phase Fractions in Heterogeneous Stress States during Multiaxial Loading of Biomedical Superelastic NiTi
Autor: | E. Andrew Payzant, Douglas E. Nicholson, Santo Padula, Dayakar Penumadu, Othmane Benafan, Jeffrey R. Bunn, Ke An, Raj Vaidyanathan |
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Rok vydání: | 2020 |
Předmět: |
Materials science
R-Phase 02 engineering and technology 010402 general chemistry 01 natural sciences Phase Transition Isothermal process Weight-Bearing Thermoelastic damping Nickel General Materials Science Composite material Titanium Mechanical Engineering Stress–strain curve Torsion (mechanics) Shape-memory alloy 021001 nanoscience & nanotechnology Microstructure Elasticity 0104 chemical sciences Deformation mechanism Mechanics of Materials Mechanical Tests Stress Mechanical 0210 nano-technology |
Zdroj: | Advanced Materials. 33:2005092 |
ISSN: | 1521-4095 0935-9648 |
Popis: | Thermoelastic deformation mechanisms in polycrystalline biomedical-grade superelastic NiTi are spatially mapped using in situ neutron diffraction during multiaxial loading and heating. The trigonal R-phase is formed from the cubic phase during cooling to room temperature and subsequently deforms in compression, tension, and torsion. The resulting R-phase variant microstructure from the variant reorientation and detwinning processes are equivalent for the corresponding strain in tension and compression, and the variant microstructure is reversible by isothermal loading. The R-phase variant microstructure is consistent between uniaxial and torsional loading when the principal stress directions of the stress state are considered (for the crystallographic directions observed here). The variant microstructure evolution is tracked and the similarity in general behavior between uniaxial and torsional loading, in spite of the implicit heterogeneous stress state associated with torsional loading, pointed to the ability of the reversible thermoelastic transformation in NiTi to accommodate stress and strain mismatch with deformation. This ability of the R-phase, despite its limited variants, to accommodate stress and strain and satisfy strain incompatibility in addition to the existing internal stresses has significance for reducing irrecoverable deformation mechanisms during loading and cycling through the phase transformation. |
Databáze: | OpenAIRE |
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