Elevated Temperature, In Situ Micromechanical Characterization of a High Temperature Ternary Shape Memory Alloy
The microthermomechanical behavior of a precipitation-hardenable Ni-48Ti-25Pd (at.%) shape memory alloy has been investigated as a function of temperature. Micropillars were fabricated within a large 〈145〉-oriented grain and compressed in situ in the SEM at elevated temperatures corresponding to the martensite and austenite phase transformation temperatures. The precipitation-strengthened alloys exhibited stable pseudoelastic behavior with little or no residual strains when near the transformation temperatures. In the plastic regime, slip was observed to occur via pencil glide, circumventing the fine scale precipitates along multiple slip planes.
KeywordsAustenite Martensite Slip Plane Applied Strain Slip Trace
MLW and GBT acknowledge the NASA grant NNX09AO61A and the NASA FAP Supersonics project, Dale Hopkins, API. The authors would like to thank D. Frey & G. Buerki for technical assistance with the in situ SEM Indenter.
- 1.P.G. Lindquist and C.M. Wayman, Shape Memory and Transformation Behavior of Martensitic Ti-Pd-Ni and Ti-Pt-Ni Alloys.Engineering Aspects of Shape Memory Alloys, ed. T.W. Duerig, K.N. Melton, D. Stöckel, and C.M. Wayman (London: Butterworth-Heinemann, 1990).Google Scholar
- 5.R. Noebe, I. Santo Padula, G. Bigelow, O. Rios, A. Garg, and B. Lerch, Properties of a Ni19. 5Pd30Ti50. 5 High-Temperature Shape Memory Alloy in Tension and Compression. Smart Structures and Materials (London: International Society for Optics and Photonics, 2006), p. 617010.Google Scholar
- 10.J.M. Wheeler, D.E.J. Armstrong, W. Heinz, and R. Schwaiger, Curr. Opin. Solid State Mater. Sci. (2015). doi: 10.1016/j.cossms.2015.02.002