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Title: Nondestructive evaluation of Ni-Ti shape memory alloy

Abstract

The nondestructive evaluation of nickel titanium (Ni-Ti) alloys for applications such as heat treatment for biomaterials applications (dental) and welding was investigated. Ni-Ti alloys and its ternary alloys are valued for mechanical properties in addition to the shape memory effect. Two analytical approaches were perused in this work. Assessment of the microstructure of the alloy that determines the martensitic start temperature (Ms) of Ni-Ti alloy as a function of heat treatment, and secondly, an attempt to evaluate a Friction Stir Welding, which involves thermo-mechanical processing of the alloy.

Authors:
; ; ; ;  [1];  [2]
  1. Department of Metallurgical and Materials Engineering, Colorado School of Mines, Golden, CO (United States)
  2. Netania (Israel)
Publication Date:
OSTI Identifier:
21511612
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1335; Journal Issue: 1; Conference: Review of progress in quantitative nondestructive evaluation, San Diego, CA (United States), 18-23 Jul 2010; Other Information: DOI: 10.1063/1.3592072; (c) 2011 American Institute of Physics
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; BINARY ALLOY SYSTEMS; CHARGES; EDDY CURRENT TESTING; EVALUATION; FRICTION; HEAT TREATMENTS; MARTENSITIC STEELS; MECHANICAL PROPERTIES; MICROSTRUCTURE; NICKEL ALLOYS; NITRIC OXIDE; NONDESTRUCTIVE ANALYSIS; SHAPE MEMORY EFFECT; TERNARY ALLOY SYSTEMS; TITANIUM ALLOYS; WELDING; ALLOY SYSTEMS; ALLOYS; CARBON ADDITIONS; CHALCOGENIDES; CHEMICAL ANALYSIS; ELECTROMAGNETIC TESTING; FABRICATION; IRON ALLOYS; IRON BASE ALLOYS; JOINING; MATERIALS TESTING; NITROGEN COMPOUNDS; NITROGEN OXIDES; NONDESTRUCTIVE TESTING; OXIDES; OXYGEN COMPOUNDS; STEELS; TESTING; TRANSITION ELEMENT ALLOYS

Citation Formats

Meir, S., Gordon, S., Karsh, M., Ayers, R., Olson, D. L., and Wiezman, A.. Nondestructive evaluation of Ni-Ti shape memory alloy. United States: N. p., 2011. Web. doi:10.1063/1.3592072.
Meir, S., Gordon, S., Karsh, M., Ayers, R., Olson, D. L., & Wiezman, A.. Nondestructive evaluation of Ni-Ti shape memory alloy. United States. doi:10.1063/1.3592072.
Meir, S., Gordon, S., Karsh, M., Ayers, R., Olson, D. L., and Wiezman, A.. 2011. "Nondestructive evaluation of Ni-Ti shape memory alloy". United States. doi:10.1063/1.3592072.
@article{osti_21511612,
title = {Nondestructive evaluation of Ni-Ti shape memory alloy},
author = {Meir, S. and Gordon, S. and Karsh, M. and Ayers, R. and Olson, D. L. and Wiezman, A.},
abstractNote = {The nondestructive evaluation of nickel titanium (Ni-Ti) alloys for applications such as heat treatment for biomaterials applications (dental) and welding was investigated. Ni-Ti alloys and its ternary alloys are valued for mechanical properties in addition to the shape memory effect. Two analytical approaches were perused in this work. Assessment of the microstructure of the alloy that determines the martensitic start temperature (Ms) of Ni-Ti alloy as a function of heat treatment, and secondly, an attempt to evaluate a Friction Stir Welding, which involves thermo-mechanical processing of the alloy.},
doi = {10.1063/1.3592072},
journal = {AIP Conference Proceedings},
number = 1,
volume = 1335,
place = {United States},
year = 2011,
month = 6
}
  • At present, many investigations are done on Fe-Mn-based shape memory alloys because of their particularly good one-way type shape memory effect and their low cost. With addition of Cr and Ni, it is possible to reach a good corrosion resistance, which confers to this type of alloys a commercial significance. The shape memory effect is associated with the formation of stress-induced [var epsilon]-martensite by deformation of an austenitic ([gamma]) sample. The reversion by heating of the [var epsilon]-martensite provides the shape memory effect. It is generally admitted that the presence of thermal [var epsilon]-martensite before deformation has a negative influencemore » on the formation of the stress-induced martensite and on the shape memory effect. The authors' purpose is to evaluate the real influence of the pre-existing thermal [var epsilon]-martensite on the formation of the stress-induced [var epsilon]-martensite, its recovery and on the shape memory effect.« less
  • The shape memory effect of Fe-Mn based shape memory alloys is due to the formation of stress-induced [var epsilon]-martensite by deformation and to its reversion by heating over A[sub f], which permit it to recover a part of the original shape. The shape memory effect is directly associated with the [gamma][yields][var epsilon] transformation. For this reason, the authors have established the best conditions to induce the [var epsilon]-martensite inside an austenitic matrix: the deformation must take place at a temperature close to the M[sub s]. It has been established that a deformation made at a higher temperature degrades the shapemore » memory effect. The purpose of this paper is to evaluate the shape memory effect in the case of a deformation applied at a relatively high temperature (just below A[sub s]) on samples containing a high volume fraction of [var epsilon]-martensite before the deformation. It is shown that an other mechanism of shape memory effect occurs in these conditions and allows to reach an interesting shape memory effect ([approximately]2%).« less
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  • The authors report on the near-reversible strain hysteresis during thermal cycling of a polycrystalline NiTi shape memory alloy at a constant stress that is below the yield strength of the martensite. In situ neutron diffraction experiments are used to demonstrate that the strain hysteresis occurs due to a texture memory effect, where the martensite develops a texture when it is cooled under load from the austenite phase and is thereafter ''remembered.'' Further, the authors quantitatively relate the texture to the strain by developing a calculated strain-texture map or pole figure for the martensite phase, and indicate its applicability in othermore » martensitic transformations.« less
  • It is shown that alloy based on TiNi containing Fe and elements of the Vth group does not change shape with cooling under lead in the range +20 to /minus/180/degree/C. The maximum increase in thermomechanical recovery stress up to 250 N/mm/sup 2/ is achieved with applied stresses = 200-400 N/mm/sup 2/. Martensitic transformation hysteresis increases with an increase in applied stress.