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High temperature NiTiHf shape memory thin films fabricated by simultaneous sputter deposition from elemental targets

Sanjabi, S ; Sharif University of Technology | 2008

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  1. Type of Document: Article
  2. DOI: 10.1361/cp2006smst315
  3. Publisher: 2008
  4. Abstract:
  5. NiTiHf thin films with varying hafnium contents up to 28.7at% were fabricated using simultaneous sputter deposition from separate Ni, Ti, and Hf targets onto unheated substrates. The required film composition was achieved by adjusting the power ratio to the targets. The as-deposited films were amorphous; and post deposition annealing was performed at 550°C, slightly above their crystallization temperatures. The crystallization temperature of the films varied as a function of Hf concentration, and was as high as 520°C at a Hf content of 28.7at%. 2μm thick crystallized films with I0at% or greater Hf were martensitic at room temperature. DSC analysis demonstrated that above 10at%Hf additions the transformation temperatures increased considerably over NiTi, reaching as high as 414 °C (Ap) at a Hf content of 24.4 at.%. Our results confirm that these films are comparable with bulk NiTiHf alloy of similar composition
  6. Keywords:
  7. Crystallization ; Hafnium ; Martensitic transformations ; Sputter deposition ; Targets ; Thin films ; As-deposited films ; Crystallization temperatures ; Crystallized films ; Elemental targets ; Film compositions ; HF concentrations ; High temperatures ; Post-deposition annealing ; Power ratios ; Room temperatures ; Shape memory thin films ; Transformation temperatures ; Unheated substrates ; Amorphous films
  8. Source: International Conference on Shape Memory and Superelastic Technologies, SMST-2006, Pacific Grove, CA, 7 May 2006 through 11 May 2006 ; 2008 , Pages 315-322 ; 9780871708625 (ISBN)
  9. URL: https://www.scopus.com/inward/record.uri?eid=2-s2.0-63149132090&doi=10.1361%2fcp2006smst315&partnerID=40&md5=c0bd4215e1fc233b2af12a698376de48