Dilatometer for measurements of linear dimension variations under the effects of temperature, magnetic field and mechanical stress

• Published in: Measurement science & technology 2002-02, Vol.13 (2), p.174-178
• Main Authors: Cherepin, V T, Glavatska, N I, Glavatsky, I N, Gavriljuk, V G
• Format: Article
• Language: English
• Subjects: Exact sciences and technology; General equipment and techniques; Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Magnetic components, instruments and techniques; Magnetometers for magnetic field measurements; Measurements common to several branches of physics and astronomy; Metrology, measurements and laboratory procedures; Physics; Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing; Spatial dimensions (e.g.: position, lengths, volume, angles, displacements, including nanometer-scale displacements); Spatial dimensions (eg, position, lengths, volume, angles, displacements, including nanometer-scale displacements)
• ISSN: 0957-0233; 1361-6501
• DOI: 10.1088/0957-0233/13/2/306

A multi-purpose automated dilatometer has been developed for simultaneous measurements of the expansion/contraction under the effects of magnetic field and/or mechanical stress and/or temperature. The differential capacitive position sensor, operating together with the microprocessor-controlled digital transformer bridge, is used as a displacement transducer with a resolution of several tens of nanometers. Measurements are accomplished in the temperature range from -150 to 200 C. The automatically controlled variation of the applied magnetic field is provided by an electromagnet with a field homogeneity of 0.5 OE 10 exp -5 of the magnetic field strength (maximum 1.1 T). A special controlling system is developed for the automated mechanical loading of the sample under investigation. Some examples of the measurements completed on the magnetic shape memory alloy Ni2MnGa are presented for three cases: (1) strain as a function of the applied magnetic field; (2) creep under constant magnetic field or mechanical stress; and (3) phase transformations during heating/cooling with and without the applied magnetic field. (Author)