Магнитокалорический эффект сплава MnFe2Si, легированного Cr и Fe
: магистерская диссертация

Tesis doctoral: Master's Thesis

Resumen

The alloys FeMnSi and Fe2MnCrSi were obtained in arc furnace in a helium atmosphere at the water-cooled copper ingot mold with the double remelting. Homogenizing annealing of the samples was carried out in a vacuum furnace at 950°C. X-ray analysis was carried out for structure investigation of the alloys. The diffraction patterns were obtained on the X-ray diffractometer Bruker D8 Advance, measurement results were processed using software FullProf v.2.05. Measurement of magnetization isotherms and dependences of the magnetization of alloys on magnetic field were carried out with vibration magnetometer7407 VSM (Lake Shore Cryotronics) in magnetic fields up to 1.7 T at temperature 80 – 400 K. Changes in magnetic part of entropy in various magnetic fields from 0.01 to 1.7 T calculated from isotherms. For sample Fe1.75Mn1.25Si it is shown that at the Curie temperature dependence of the changes of entropy on the magnetic field is almost linear. Obtained dependence of the magnetization on the field at temperatures Tc - 50 K (Tc – the Curie temperature) for all investigated compounds showed that the magnetization of samples decreases with increasing concentration of manganese and chromium. The Curie temperature for alloys Fe3-xMnxSi decreases with increasing of manganese concentration. For alloys Fe2Mn1-xCrxSi the Curie temperature increase with with increasing of chromium concentration. ∆T-effect for all compounds was measured by direct method on an automated installation for measurement of the specific heat and magnetocaloric effect MagEq MMS SV3 (AMT&C) in magnetic field 1.7 T at temperature 85-370 К. The magnitude of the magnetocaloric effect of the investigated compounds kept constant in the investigated manganese and chromium concentration range including at room temperature.
Fecha de adjudicación2015
Idioma originalRussian
Institución adjudicataria
  • Ural Federal University
SupervisorВалерий Харитонович Осадченко (Supervisor)

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