Structure and Properties of Ni-Rich Shape Memory Alloy Subjected to Severe Deformation and Annealing

Abstract:

Ni-rich alloy (50.8at.%Ni) was plastically deformed by compression combined with reversion oscillating torsion. The compression rate was 0.05 mm/s and the torsion frequency and angle were 1,5Hz and ±3°. After the deformation process the specimens were annealed at 350°C/1h (623K/1h) and 400°C/1h (673K/1h). Their structure and transformation characteristic were studied with the use of TEM, X-ray phase analysis and DSC measurements. TEM observation of specimens after annealing at 350°C/1h (623K/1h) indicate presence of highly deformed B2 phase. In the specimen annealed at 400°C/1h (673K/1h) additionally Ni4Ti3 precipitates and the R-phase in the B2 matrix was found. DSC measurements show that the transformation sequence changes for the deformed and then annealed samples from single step B2  B19’ transformation to the B2  R  B19’ on cooling. Also increase of R-phase transformation temperature TR with the decrease of annealing temperature was observed.

• Periodical: Solid State Phenomena (Volumes 203-204)
• Pages: 339-342
• DOI: https://doi.org/10.4028/www.scientific.net/SSP.203-204.339
• Online since: June 2013
• Authors: Danuta Stróż, Jakub Palka, Zdzisław Lekston, Agniwszka Smołka
• Keywords: Amorphization, NiTi Shape Memory Alloys, Severe Deformation

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