Abstract
The present work is devoted to study the microstructure and magnetic behavior of Mn-rich Heusler MnNiIn alloys. The Mn-substituted alloys with Mn50Ni50-xInx (at.%) (x= 7.5 and 10) were prepared by melt-spinning technique. Experimental results show that the alloys crystallized into a monoclinic martensite structure 14M type, for the Mn50Ni42.5In7.5 alloy and L2(1) type cubic austenite structure for the Mn50Ni40In10 alloy. The characteristic temperatures decreased with the increase of In content under different magnetic fields: 50 Oe, 500 Oe, 5 kOe and 30 kOe. For the Mn50Ni42.5In7.5 alloy, the presence of a paramagnetic-ferromagnetic transition is noted. This transition in the austenitic phase occurs before the martensitic transformation during cooling. On the other side, for the Mn50Ni40In10 alloy, there is the presence of a martensitic transformation followed by a ferromagnetic transition. This transformation is carried out between a paramagnetic cubic austenite type and a ferromagnetic monoclinic martensite. This allows us to conclude that Indium addition plays a role to change the structure and magnetic behavior in MnNiIn alloys.