  Magnetocaloric materials have received significant attention of research
community as they can minimize the use of harmful gases (CFCs, HFCs) and render
eco-friendly refrigeration. Heusler alloys (Ni2MnGa) are known for their
magnetocaloric effects, which make them useful as energy efficient and
eco-friendly refrigerating materials. Magnetocaloric properties significantly
depend on the composition of these alloys. Ni-Mn-Ga is one of the interesting
Heusler systems, which exhibits magnetocaloric properties. In the present
study, we performed the thermodynamic optimization of two sub binaries of the
Ni-Mn-Ga system: Mn-Ga and Ni-Ga, using CALPHAD approach. A Modified
Quasichemical Model (MQM) was used to describe the thermodynamic properties of
the liquid solutions in both the binaries. Both the binaries were combined with
Mn-Ni to develop a self-consistent thermodynamic database for Ni-Mn-Ga. In
order to resolve the existing experimental discrepancies in the Mn-Ga and Ni-Ga
system, few alloy compositions were prepared and analyzed using differential
thermal analysis. Finally, the developed thermodynamic database was used to
calculate the ternary isothermal section of the Ni-Mn-Ga (Heusler alloy) system
at 1073 K with a proposed phase region for magnetocaloric applications.
