Irradiation-induced softening of Ni3P and (Ni,Fe,Cr)3P alloys

Production of amorphous alloys by solid state reactions (SSR) has attracted much interest during the last few years. One of the methods to induce such a reaction is the irradiation of suitable crystalline alloys by fast particles. Examination of this kind of SSR in M[sub 3]P type of brazing alloys (M: Metal) is attractive because of the following reason: In brazed joints of candidate structural materials like 316L stainless steel for applications in fusion reactors, crystalline intermetallic phases have been detected which are unstable relative to the amorphous state when irradiated at moderate temperatures with fast particles. It is expected that the transition to the amorphous state is accompanied by changes of the mechanical properties, which are of fundamental interest in this context. Until now, only a few studies on the evolution of mechanical properties during amorphization have been performed. Measurements of microhardness of the crystalline and the corresponding amorphous phase do not exist to the authors knowledge. In this communication, the authors present results on changes of microhardness, due to amorphization by fast ions. The measurements have been performed on a model alloy Ni[sub 3]P and on the brazed joint of stainless steel 316L, containing M[sub 3]P (M: Ni,more » Fe, Cr) as one of the phases. Though microhardness is not a fundamental property of materials, it is a manifestation of several related properties, such as yield stress, ductility, work-hardening, elastic modulus and residual stress states. It represents a resistance for indentation and is, therefore, appropriate for comparative purposes.« less