Optimizing the Caloric Properties of Cu-Doped Ni–Mn–Ga Alloys
| Autor: | Joan Torrens-Serra, Eduard Cesari, Patricia Lázpita, Concepcio Seguí |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
magnetocaloric effect
Materials science Alloy Thermodynamics 02 engineering and technology engineering.material lcsh:Technology 01 natural sciences Article Isothermal process Magnetization Paramagnetism elastocaloric effect 0103 physical sciences Magnetic refrigeration General Materials Science cu-doped ni–mn–ga lcsh:Microscopy ferromagnetic shape memory alloys lcsh:QC120-168.85 010302 applied physics Austenite lcsh:QH201-278.5 lcsh:T 021001 nanoscience & nanotechnology hysteresis Ferromagnetism lcsh:TA1-2040 Martensite engineering lcsh:Descriptive and experimental mechanics lcsh:Electrical engineering. Electronics. Nuclear engineering entropy lcsh:Engineering (General). Civil engineering (General) 0210 nano-technology lcsh:TK1-9971 |
| Zdroj: | Materials, Vol 13, Iss 2, p 419 (2020) Materials Volume 13 Issue 2 |
| ISSN: | 1996-1944 |
| DOI: | 10.3390/ma13020419 |
| Popis: | With the purpose to optimize the functional properties of Heusler alloys for their use in solid-state refrigeration, the characteristics of the martensitic and magnetic transitions undergone by Ni50Mn25&minus xGa25Cux (x = 3&ndash 11) alloys have been studied. The results reveal that, for a Cu content of x = 5.5&ndash 7.5, a magnetostructural transition between paramagnetic austenite and ferromagnetic martensite takes place. In such a case, magnetic field and stress act in the same sense, lowering the critical combined fields to induce the transformation moreover, magnetocaloric and elastocaloric effects are both direct, suggesting the use of combined fields to improve the overall refrigeration capacity of the alloy. Within this range of compositions, the measured transformation entropy is increased owing to the magnetic contribution to entropy, showing a maximum at composition x = 6, in which the magnetization jump at the transformation is the largest of the set. At the same time, the temperature hysteresis of the transformation displays a minimum at x = 6, attributed to the optimal lattice compatibility between austenite and martensite. We show that, among this system, the optimal caloric performance is found for the x = 6 composition, which displays high isothermal entropy changes (&minus 36 J· kg&minus 1· K&minus 1 under 5 T and &minus 8.5 J· 1 under 50 MPa), suitable working temperature (300 K), and low thermal hysteresis (3 K). |
| Databáze: | OpenAIRE |
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