New Interpretation of the Electrical Resistivity Measurements for Obtaining NiTi SMA Stress-Free Transformation Temperatures

The objective of this study is to clarify and to improve the interpretation of the ER measurements used to obtain NiTi SMA stress-free transformation temperatures for the austenite to martensite transformation process. To achieve this objective, the transformation temperatures of NiTi SMA wires are measured by ER using the Ling and Kaplow interpretation and are compared and complemented by weight fraction diagrams. The weight fractions are obtained from XRD profiles using the Parametric Rietveld refinement and adequate software. As a result of comparing both techniques, a new interpretation of the ER curves is proposed. This new interpretation is based on the shape of NiTi ER curve, which depends on the quantity of R-phase in the NiTi SMA. The quantity of the R-phase is obtained by weight fraction diagrams. According to the findings presented here, a new criterion for R-phase and martensite transformation temperatures is proposed.

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In-situ electrical-resistivity measurements in the high-voltage electron microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100107484 ◽

1978 ◽

Vol 36 (1) ◽

pp. 68-69

Author(s):

W. E. King

Keyword(s):

Electrical Resistivity ◽

Electron Microscope ◽

High Voltage ◽

Resistivity Measurements ◽

Voltage Electron ◽

High Voltage Electron Microscope ◽

High Voltage Electron ◽

Wide Range ◽

Helium Gas

A side-entry type, helium-temperature specimen stage that has the capability of in-situ electrical-resistivity measurements has been designed and developed for use in the AEI-EM7 1200-kV electron microscope at Argonne National Laboratory. The electrical-resistivity measurements complement the high-voltage electron microscope (HVEM) to yield a unique opportunity to investigate defect production in metals by electron irradiation over a wide range of defect concentrations.A flow cryostat that uses helium gas as a coolant is employed to attain and maintain any specified temperature between 10 and 300 K. The helium gas coolant eliminates the vibrations that arise from boiling liquid helium and the temperature instabilities due to alternating heat-transfer mechanisms in the two-phase temperature regime (4.215 K). Figure 1 shows a schematic view of the liquid/gaseous helium transfer system. A liquid-gas mixture can be used for fast cooldown. The cold tip of the transfer tube is inserted coincident with the tilt axis of the specimen stage, and the end of the coolant flow tube is positioned without contact within the heat exchanger of the copper specimen block (Fig. 2).

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Electrical Resistivity Measurements and Soundings on Glaciers: Introductory Remarks

Journal of Glaciology ◽

10.1017/s0022143000019870 ◽

1967 ◽

Vol 6 (47) ◽

pp. 599-606 ◽

Cited By ~ 29

Author(s):

Hans Röthlisberger

Keyword(s):

Electrical Resistivity ◽

Resistivity Measurements ◽

Resistivity Method

A brief description of the resistivity method is given, stressing the points which are of particular importance when working on glaciers. The literature is briefly reviewed.

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Influence of material parameters on 2D-martensitic transformation based on the phase-field finite-element method

Metallurgical Research & Technology ◽

10.1051/metal/2019036 ◽

2019 ◽

Vol 116 (6) ◽

pp. 614

Author(s):

Li Chang ◽

Gao Jingxiang ◽

Zhang Dacheng ◽

Chen Zhengwei ◽

Han Xing

Keyword(s):

Finite Element Method ◽

Finite Element ◽

Phase Transformation ◽

Martensitic Transformation ◽

Phase Field ◽

Martensite Transformation ◽

Transformation Process ◽

Martensite Phase ◽

Phase Field Method ◽

Element Method

Obtaining an accurate microscopic representation of the martensitic transformation process is key to realizing the best performance of materials and is of great significance in the field of material design. Due to the martensite phase transformation is rapidly, the current experimental is hard to capture all the information in the Martensite phase transformation process. Combining the phase-field method with the finite-element method, a model of martensitic transformation from a metastable state to a steady state is established. The law of a single martensite nucleus during martensitic transformation is accurately described. By changing the key materials that affect martensite transformation and the phase-field parameters, the effects of the parameters on the single martensitic nucleation process are obtained. This study provides an important theoretical basis for effectively revealing the essence of martensite transformation and can determine effective ways to influence martensite transformation, obtain the optimal parameters and improve the mechanical properties of such materials.

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Characterization of microstructural changes in an Al-6.8wt.% Mg alloy by electrical resistivity measurements

Materials Science and Engineering A ◽

10.1016/j.msea.2008.04.001 ◽

2008 ◽

Vol 492 (1-2) ◽

pp. 460-467 ◽

Cited By ~ 43

Author(s):

Miljana Popović ◽

Endre Romhanji

Keyword(s):

Electrical Resistivity ◽

Mg Alloy ◽

Microstructural Changes ◽

Resistivity Measurements

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STUDY OF THE DEPENDENCE OF HIGH Tc ON VARIOUS SINTERING TEMPERATURES FOR Bi-Pb-Sr-Ca-Cu-O SUPERCONDUCTORS

Modern Physics Letters B ◽

10.1142/s0217984991001969 ◽

1991 ◽

Vol 05 (24n25) ◽

pp. 1635-1638

Author(s):

S.M. M.R. NAQVI ◽

A.A. QIDWAI ◽

S.M. ZIA-UL-HAQUE ◽

FIROZ AHMAD ◽

S.D.H. RIZVI ◽

...

Keyword(s):

Electrical Resistivity ◽

Liquid Nitrogen ◽

X Ray Diffraction ◽

High Tc ◽

X Ray ◽

Resistivity Measurements ◽

Zero Resistance

Bi1.7-Pb0.3-Sr2-Ca2-Cu3-Ox superconducting samples were prepared at 855°C, 862 C, 870 C, and 882 C sintering temperatures respectively. All samples were sintered for 120 hours. The samples were then quenched in liquid nitrogen. The electrical resistivity measurements showed that the samples sintered at 870° C had the best Tc. For these samples the Tc onset was around 120 K and the zero resistance was obtained at 108 K. X-ray diffraction studies showed that the samples were multiphased.

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