Influence of boron addition on the microstructure, structural and magnetic properties of Ni53.5Mn26.0Ga20.5 alloy

► Addition of boron altered the modulation from 7 M to 5 M retaining monoclinic structure. ► Rise in segregation of Ni-rich secondary phase at grain boundaries with B content. ► Lower Ni content in matrix phase accounts for increased magnetization with B content. ► Lowering of martensitic transformation temperature is correlated to compositional shift.