Cascade effect on relative stability of ordered phases in Ni₄Mo under irradiation

Irradiation-induced inversion of the relative stability of two ordered phases as well as a domain of bistability have been reported in Ni₄Mo under electron irradiation. In the case where irradiation effects result in two processes acting in parallel (thermally activated atom jumps and ballistic jumps) we describe the order-disorder transitions in Ni₄Mo by master equation and Fokker-Planck equation techniques. The relative stability of the two ordered phases can be discussed. The introduction of ballistic jumps by bursts (replacement cascades) does not change the steady state values of the order parameters but affects the relative stability of the phases. The larger the cascade size is, the larger the domain of inversion of stability.