Fatigue properties of NiTi shape-memory alloy thin plates

Yamamoto, Hiroshi; Taya, Masahito; Liang, Yuan‐Chang; Namli, Onur C.; Saitô, Makoto

doi:10.1117/12.2009857

Cited by 2 publications

(1 citation statement)

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“…[Figure 1 placed approximately here] Under displacement-controlled cyclic loading, superelastic compositions of Nickel Titanium exhibit functional fatigue (Eggeler et al, 2004;Kang, 2013;Kang et al, 2009;Kim and Daly, 2010;Kumar et al, 2011;Norfleet et al, 2009;Pelton, 2011;Richards et al, 2013;Yamamoto et al, 2013). Functional fatigue is defined by a shift in the characteristic strains and stresses associated with martensitic transformation and recovery during cycling, as shown in Figure 1.…”

Section: Introductionmentioning

confidence: 99%

The effect of microstructure on stress-induced martensitic transformation under cyclic loading in the SMA Nickel-Titanium

Kimiecik

Jones

Daly

2016

Journal of the Mechanics and Physics of Solids

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A combined experimental and analytical study to determine the configurations of transforming martensite during ambient temperature cyclic deformation of superelastic Nickel-Titanium has been conducted. Full-field, sub-grain-size microscale strain measurements were made in situ during cycling using distortion-corrected Digital Image Correlation combined with Scanning Electron Microscopy (SEM-DIC). Using grain orientation maps from Electron Backscatter Diffraction analysis, possible configurations of martensite formed during cyclic deformation were identified by matching the calculated and measured strain fields. This analysis showed that the inclusion of Correspondence Variants (CVs) in addition to Habit Plane Variants (HPVs) of transformed martensite was necessary to provide a robust fit between calculated and measured strain fields. The approach also provided evidence that there was a more rapid accumulation of residual strain in CV regions and that a correlation existed between residual strain accumulation and the loss of actively transforming martensite in later cycles. It was also found that regions of CVs could coexist with untransformed austenite and Habit Plane Variants (HPVs) in individual grains throughout the microstructure, and that these regions of CVs formed before the end of the macroscopic stress plateau. The CV structure that forms during the initial superelastic deformation of Nickel-Titanium plays a critical role in shaping and stabilizing subsequent martensite recovery during cyclic loading.

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