Among the ferromagnetic Heusler alloys, those derived from Ni-Mn-Ga system have been widely studied owing to exciting phenomena like large magnetic field induced strain, magnetocaloric effect, magnetoresistance or high temperature shape memory effect that have been observed in them at different compositions. In order to tune the properties of the Ni-Mn-Ga alloys, one can either vary its composition or introduce other elements by substitution. Since boron has a tendency to cause second phase segregation, it is interesting to study the influence of boron on the crystal structure, microstructural, magnetic and mechanical properties of Ni- Mn-Ga alloys. Correlation of transformation temperatures and magnetic properties to microstructural alterations brought about by boron is worth being studied. A modified scheme to compute electron concentration, which can predict the martensitic transformations of ternary and quasi-ternary Ni-Mn-(Ga, Sb,Sn and Al)-(C0, Fe, In) systems.

Autorentext

Ramudu Machavarapu received his Ph.D. degree in Physic from University of Hyderabad, India in 2012. He worked on ferromagnetic shape memory alloys of Ni-Mn-Ga system and the effect of boron addition on its properties. Presently, he is working on ferromagnetic shape memory thin films, at Johannes Gutenberg University of Mainz,Germany.