Microstructural studies of NiCoMnln magnetic shape memory ribbons

摘要

In present paper two ribbons of the Ni_(44)Co_6Mn_(36)In_(14) (at.%) were prepared under different melt-spinning technique conditions. Microstructure of the ribbons was studied by scanning electron microscopy (SEM). Depending on the liquid ejection overpressure two types of ribbons microstructures were observed. Ribbon T1 for which ejection overpressure was 1.5 bar showed typical melt-spun ribbon microstructure consisting of a top layer of small equi-axial grains and columnar grains below. For T2 ribbon (ejection overpressure 0.2 bar) only a small fraction of the columnar grains were observed. Structure analysis of the ribbons performed by X-ray Diffraction (XRD) showed that at room temperature both ribbons have B2 parent phase superstructure. No γ phase precipitates were observed. In order to determine the orientation of the grains the Electron Backscatter Diffraction (EBSD) technique was applied.