Abstract

Single phase microcrystalline ribbon flakes with the average elemental composition Ni50.4Mn34.9In14.7 were produced by rapid quenching using melt spinning technique. Fracture cross section micrographs of ribbons show the formation of a columnar-like microstructure, with the longer axis of grains aligned perpendicular to ribbon plane. X-ray diffraction and thermomagnetic analysis show that samples are single phase with L2(1)-type austenite as high-temperature parent phase ( Curie point of 284 K). At low temperatures austenite transforms into a ten-layered structurally modulated monoclinic martensite. The characteristic phase transition temperatures and thermal hysteresis of the reversible martensite-austenite transformation were M-S = 262 K, M-f = 245 K, AS = 262 K, A(f) = 270K and Delta T = 10 K. The crystalline directions [2 2 0] of austenite and [1 2 5] of martensite were found preferentially oriented normal to the ribbon plane. The measurement of magnetization isotherms up to 80 kOe confirmed the occurrence of the field-induced reverse martensitic transformation.