Stability of phosphorus intermetallic compounds during irradiation of nickel-based alloys used in brazings

In order to simulate the effect of high energy neutrons on the stability of phases in phosphorus brazing alloys, irradiations with He, Ne, Kr, Ni ions have been performed. The problem is to study the microstructural evolution of phosphides (M₂P and M₃P) present in junctions formed by brazing with an emphasis on amorphization in relation with cascade size effect. Our irradiated materials include a brazed junction of two stainless steel plates, two amorphous model alloys and a crystalline model alloy. Irradiations were performed at a dose equivalent to 10 dpa at 303 and 523 K. We observed that at 303 K the amorphous state was stable for M₃P. At the higher temperature of 523 K, the amorphous alloys recrystallized and a dislocation network was developed in the three phases present in the junction. The formation of the amorphous phase was discussed in the light of a phase stability model.