Probing Martensitic Transition in Nitinol Wire: A Comparison of X-ray Diffraction and Other Techniques

Journal Article · Mon Jan 17 00:00:00 EST 2011 · AIP Conference Proceedings

DOI:https://doi.org/10.1063/1.3552318· OSTI ID:21510137

Butler, J; Tiernan, P; Tofail, S A. M.; Ghandi, A A ^[1]

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1. Materials and Surface Science Institute, University of Limerick, Limerick (Ireland)

Martensitic to austenite transformation in Nitinol wire can be measured by a number of techniques such as XRD (X-Ray Diffraction), DSC (Differential Scanning Calorimetry), BFR (Bend and Free Recovery) and Vickers indentation recovery. A comparison of results from these varied characterisation techniques is reported here to obtain a greater understanding of the thermal-elastic-structural changes associated with martensitic transformation. The transformation temperatures measured by DSC were found to correspond well with the structural and mechanical information obtained from XRD, BFR and Vickers indent recovery methods. Indent recovery is a relatively new and accurate method of monitoring stress induced martensitic transformations in NiTi and is one of only a few methods of stress inducing martensitic transformation in large scale samples. It is especially useful for NiTi in the as-cast billet form, where tensile testing is impossible. BFR is uniquely popular in the NiTi wire manufacturing sector and is recognised as the most accurate method of measuring the transformation temperature. Here the material is stressed to a representative in-service stress level during the test. No other test uses the shape memory effect for measuring the transformation temperature of NiTi. The results show that the DSC thermogram and XRD diffractogram have a peak overlap which is a common occurrence in NiTi that has been extensively processed. The XRD method further explains the observations in the DSC thermogram and in combination they confirm the transformation temperature.

• OSTI ID: 21510137
• Journal Information: AIP Conference Proceedings, Vol. 1315, Issue 1; Conference: AMPT2010: International conference on advances in materials and processing technologies, Paris (France), 24-27 Oct 2010; Other Information: DOI: 10.1063/1.3552318; (c) 2010 American Institute of Physics; ISSN 0094-243X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
AUSTENITE
CALORIMETRY
COMPARATIVE EVALUATIONS
CRYSTAL-PHASE TRANSFORMATIONS
MANUFACTURING
MARTENSITIC STEELS
NICKEL ALLOYS
PHASE TRANSFORMATIONS
SHAPE MEMORY EFFECT
STRESSES
TITANIUM ALLOYS
TRANSFORMATIONS
WIRES
X-RAY DIFFRACTION
ALLOYS
CARBON ADDITIONS
COHERENT SCATTERING
DIFFRACTION
EVALUATION
IRON ALLOYS
IRON BASE ALLOYS
SCATTERING
STEELS
TRANSITION ELEMENT ALLOYS