Effect of Ni/Mn ratio on phase transformation and magnetic properties in Ni-Mn-ln alloys

摘要

The effect of variation in Ni/Mn ratio on structure, phase transformation, and magnetic properties was investigated in the Ni_(50-x)Mn_(37+x)In_(13) alloys. Small change in the Ni/Mn ratio drives the structure from martensite of tetragonal L1_0 to austenite of cubic L2_1 at room temperature. With decrease in Ni/Mn ratio or increase in Mn content the martensitic transformation temperature was found to decrease and the alloys do not undergo phase transformation below a critical value (7.86) of valence electron concentration (e/a). Temperature and field dependence of magnetization data reveals the complex magnetic nature arising from the coexistence of ferromagnetic and antiferromagnetic interactions in the system. It was found that the effect of Ni/Mn and Mn/In ratios on phase transformation and magnetic properties in Ni-Mn-ln alloys is similar if the e/a value of the alloy system remains unchanged.