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Strain relaxation in Cu-Al-Ni shape memory alloys studied by in situ neutron diffraction experiments
- Source :
- Addi. Archivo Digital para la Docencia y la Investigación, instname
- Publication Year :
- 2019
- Publisher :
- AIP Publishing, 2019.
-
Abstract
- In situ neutron diffraction is used to study the strain relaxation on a single crystal and other powdered Cu-Al-Ni shape memory alloys (SMAs) around martensitic transformation temperatures. This work is focused on the analysis of the strain evolution along the temperature memory effect appearing in these alloys after partial thermal transformations. A careful study of the influence of partial cycling on the neutron diffraction spectra in the martensitic phase is presented. Two different effects are observed, the d-spacing position shift and the narrowing of various diffraction peaks, along uncompleted transformation cycles during the thermal reverse martensitic transformation. These changes are associated with the relaxation of the mechanical stresses elastically stored around the martensitic variants, due to the different self-accommodating conditions after uncompleted transformations. The evolution of the stresses is measured through the strain relaxation, which is accessible by neutron diffraction. The observed effects and the measured strain relaxations are in agreement with the predictions of the model proposed to explain this behavior in previous calorimetric studies. In addition, the thermal expansion coefficients of both martensite and austenite phases were measured. The neutron experiments have allowed a complete description of the strains during martensitic transformation, and the obtained conclusions can be extrapolated to other SMA systems.In situ neutron diffraction is used to study the strain relaxation on a single crystal and other powdered Cu-Al-Ni shape memory alloys (SMAs) around martensitic transformation temperatures. This work is focused on the analysis of the strain evolution along the temperature memory effect appearing in these alloys after partial thermal transformations. A careful study of the influence of partial cycling on the neutron diffraction spectra in the martensitic phase is presented. Two different effects are observed, the d-spacing position shift and the narrowing of various diffraction peaks, along uncompleted transformation cycles during the thermal reverse martensitic transformation. These changes are associated with the relaxation of the mechanical stresses elastically stored around the martensitic variants, due to the different self-accommodating conditions after uncompleted transformations. The evolution of the stresses is measured through the strain relaxation, which is accessible by neutron diffraction. The...
- Subjects :
- Diffraction
elastic-constants
Materials science
Neutron diffraction
General Physics and Astronomy
02 engineering and technology
01 natural sciences
Thermal expansion
stress
Condensed Matter::Materials Science
superelasticity
0103 physical sciences
Stress relaxation
austenite
010302 applied physics
Austenite
Condensed matter physics
beta-phase
scattering
temperature
021001 nanoscience & nanotechnology
Martensite
Diffusionless transformation
Relaxation (physics)
0210 nano-technology
martensitic-transformation
incomplete transformation
Subjects
Details
- ISSN :
- 10897550 and 00218979
- Volume :
- 125
- Database :
- OpenAIRE
- Journal :
- Journal of Applied Physics
- Accession number :
- edsair.doi.dedup.....c24862388cce5a5e8e2f7022c264bd3b