Stress Induced Martensitic Transformation in NiTi at Elevated Temperatures: Martensite Variant Microstructures, Recoverable Strains and Plastic Strains
SSRN, ISSN: 1556-5068
2024
- 112Usage
Metric Options: Counts1 Year3 YearSelecting the 1-year or 3-year option will change the metrics count to percentiles, illustrating how an article or review compares to other articles or reviews within the selected time period in the same journal. Selecting the 1-year option compares the metrics against other articles/reviews that were also published in the same calendar year. Selecting the 3-year option compares the metrics against other articles/reviews that were also published in the same calendar year plus the two years prior.
Example: if you select the 1-year option for an article published in 2019 and a metric category shows 90%, that means that the article or review is performing better than 90% of the other articles/reviews published in that journal in 2019. If you select the 3-year option for the same article published in 2019 and the metric category shows 90%, that means that the article or review is performing better than 90% of the other articles/reviews published in that journal in 2019, 2018 and 2017.
Citation Benchmarking is provided by Scopus and SciVal and is different from the metrics context provided by PlumX Metrics.
Example: if you select the 1-year option for an article published in 2019 and a metric category shows 90%, that means that the article or review is performing better than 90% of the other articles/reviews published in that journal in 2019. If you select the 3-year option for the same article published in 2019 and the metric category shows 90%, that means that the article or review is performing better than 90% of the other articles/reviews published in that journal in 2019, 2018 and 2017.
Citation Benchmarking is provided by Scopus and SciVal and is different from the metrics context provided by PlumX Metrics.
Article Description
In order to shed light on the origin of the loss of functional properties of NiTi with increasing temperature, we have investigated stress induced martensitic transformations in nanocrystalline NiTi shape memory wire by a special kind of thermomechanical testing supplemented with post-mortem reconstruction of martensite variant microstructures in grains of deformed wires by transmission electron microscopy.It is found that the forward stress induced martensitic transformation is not completed at the end of the stress plateau and generates unrecoverable plastic strain in addition to recoverable transformation strain. The higher the test temperature, the larger is the plastic strain as well as the volume fraction of retained austenite. The reconstructed martensite variant microstructures in grains of the NiTi wire deformed up to the end of the stress plateau at 120 °C were found to be filled with single domains of (001) compound twin laminate, some grains were nearly detwinned and some grains contained (100) deformation twins. The recoverable transformation strain (~6%) generated by the forward martensitic transformation is nearly independent on the test temperature (plateau stress) because detwinning of (001) compound twins in the microstructure is prohibited by lateral constraint from the surrounding grains in nanocrystalline wire.It is concluded that the gradual loss of functionality of NiTi with increasing temperature does not originate from the plastic deformation of austenite, as widely assumed in the literature, but that it derives from the lack of resistance of the stress induced martensite to the plastic deformation under increasing stress.
Bibliographic Details
Provide Feedback
Have ideas for a new metric? Would you like to see something else here?Let us know