Structural behavior of Ni-Mn-(In, Sn) Heusler melt spun ribbons

Abstract
In present contribution we discuss the structural properties of the austenite and martensite phases that form in as-spun ribbons of some selected compositions of the ternary system Ni₅₀Mn_50-x(In,Sn)_x, their characteristic crystallographic texture and the effect of vacuum annealing. X-Ray diffraction analysis showed that in all the cases austenite crystallized in an ordered cubic L2₁-type structure. For thermally annealed samples diffraction lines becomes narrower in comparison with those of as-quenched samples, cell parameters tend reduce and crystallographic texture is preserved and improved. Furthermore, the structure and the martensitic temperature transformation can significantly differ from that of bulk alloys. Thus, materials with different structure, magnetoelastic behavior and transformation temperatures can be produced by melt spinning controlling starting composition and quenching conditions. In textured ribbons, the columnar, almost 1-dimensional, shape of the grains makes structural changes more difficult than in bulk materials (3-dimensional shape), thus explaining the differences observed in their structure and temperature magnitudes involved.