Martensitic transformation and magnetic behavior in Mn-rich Heusler MnNiIn shape memory alloys

摘要

The present work is devoted to study the microstructure and magnetic behavior of Mn-rich Heusler MnNiln alloys.The Mn-substituted alloys with Mn_(50)Ni_(50-x)Inx(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 Mn_(50)Ni_(42.5)ln_(7.5)alloy and L21 type cubic austenite structure for the Mn_(50)Ni_(40)In_(10)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 Mn_(50)Ni_(425)In_(7.5)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 Mn_(50)Ni_(40)In_(10)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 MnNiln alloys.