Structural evolution of magnetron sputtered shape memory alloy NiTi films
Structural evolution of magnetron sputtered shape memory alloy NiTi films
Martins, R. M. S.; Schell, N.; von Borany, J.; Mahesh, K. K.; Silva, R. J. C.; Braz Fernandes, F. M.
Near equiatomic and Ti-rich NiTi polycrystalline films have been deposited by magnetron co-sputtering using a chamber installed at a synchrotron radiation beamline. The in situ X-ray diffraction studies enabled the identification of different steps of the structural evolution during film processing.
The depositions on a 140 nm amorphous SiO2 buffer layer heated at 520°C (without applying bias voltage, Vb, to the substrate) led to a preferential growth of <100> oriented grains of the NiTi B2 phase from the beginning of film growth until the end of the deposition.
Films exhibiting a preferential growthof <110> oriented grains of the NiTi B2 phase from the beginning of the deposition were obtained (without and with a Vb of - 45 V) by using a TiN coating with a topmost layer formed by <111> oriented grains. Those trends have been observed for the growth of near equiatomic (~50.0 at.% TiNi) and Ti-rich (~50.8 at.% TiNi) NiTi films.
Additionally, an ion gun had been commissioned, which allows ion bombardment during sputter deposition or post-deposition ion irradiation. In this first series of experiments, a NiTi film was irradiated with He ions after deposition (without exposing the film to the atmosphere, i.e., avoiding surface oxide formation), thus modifying deliberately the microstructure of the film locally.
Keywords: Deposition by sputtering; NiTi Shape memory alloy (SMA); In situ X-ray diffraction (XRD); Texture development; Ion bombardment
Involved research facilities
- Rossendorf Beamline at ESRF DOI: 10.1107/S1600577520014265
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