The effect of low temperature thermal annealing on the magnetic properties of Heusler Ni-Mn-Sn melt-spun ribbons

Abstract

We report the effect of low temperature vacuum annealing (823 K; 550 degrees C) on the elemental chemical composition, structural phase transition temperatures, phase structure, and magnetic properties of Ni50.6Mn36.3Sn13.1 as-solidified ribbons. Their elemental chemical composition, highly oriented columnar-like microstructure and single-phase character (L2(1)-type crystal structure for austenite) remain unchanged after this low temperature annealing. Annealed ribbons show a reduction of interatomic distances which lead to a small change in the characteristic phase transition temperatures (similar to 3-6 K) but to a significant rise of similar to 73 and 63% in the saturation magnetization of the martensite and austenite phases, respectively, that can be strictly ascribed to the strengthening of ferromagnetic interactions due to the change in interatomic distances. (C) 2015 Elsevier B.V. All rights reserved.