Details

Autor(en) / Beteiligte

• Dey, Sushmita
• Roy, R.K.
• Ghosh, M.
• Basu Mallick, A.
• Mitra, A.
• Panda, A.K.

Titel

Enhancement in magnetocaloric properties of NiMnGa alloy through stoichiometric tuned phase transformation and magneto-thermal transitions

Ist Teil von

• Journal of magnetism and magnetic materials, 2017-10, Vol.439, p.305-311

Ort / Verlag

Amsterdam: Elsevier B.V

Erscheinungsjahr

2017

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• •Magnetocaloric effect in a series of NiMnGa ingot is addressed.•The alloy series included materials with austenitic phase and austenite-martensite and modulated martensite combined state.•The morphology of the ingots has been shown and discussed through phase analysis.•Influence of intermartensitic transformation on magnetic entropy change and relative cooling power is discussed.•Influence of intermartensitic state on magnetization plots and differential scanning calormetry has also been shown. The investigation is focussed on phase generation and magnetocaloric properties of a series of Ni77-XMnXGa23 (x=22, 23, 24, 25, 27) alloys prepared through arc melting furnace. With increase in Mn content, the alloys showed systematic transition from a non-modulated martensite (NM) to a fully austenitic parent phase through an appearance and coexistence of modulated (M) structure. Intermediate Mn containing alloy (#Mn24) not only displayed high magnetic entropy change (ΔSM) of −7.7J/kg−1K−1 but also large Refrigerant Capacity (RC) of 169J.Kg−1 at magnetic field change of 3 T compared to other alloys. The coexisting martensite (NM, M) and parent austenite as well as overlapping thermomagnetic and structural transformation was deliverable through tuning of alloy chemistry wherein Ni was systematically substituted by Mn. Transmission electron microscopy (TEM) supported the proposition with existence of martensite plates of different morphology in Mn24 alloy exhibiting superior magnetocaloric properties.