The thermodynamics of binary systems has been definitively assessed in the past century, and the stability of the bulk phases as a function of thermodynamic parameters such as temperature, pressure, and composition is nowadays well known. However, the kinetic conditions more recently implemented to manipulate materials usually nullify the thermodynamics prerequisites (namely, infinite volume and infinite time), thus allowing the occurrence of systems and phases (ie, different micro-structural arrangements) away from the constrains reported in the available phase diagrams. In this contest, the Ni-Si reaction couple has been attracting the interest of the material scientists since a rich variety of reaction pathways can be exploited to fabricate structures with tailored and/or innovative properties. As a matter of fact, a thorough understanding of the phenomena involved in Ni …