Influence of stacking faults and alloy composition on irradiation induced amorphization of ZrCr₂, ZrFe₂ and Zr₃(Fe_1-x,Ni_x)

The Zr-based intermetallic compounds ZrCr₂, ZrFe₂ and Zr₃(Fe_1-1,Ni_x) were irradiated with high energy electrons at the HVEM/Tandem facility at Argonne National Laboratory to study their amorphization behavior. The results show that although ZrCr₂ and ZrFe₂ have the same Laves phase C15 fcc crystal structure, their critical temperatures for amorphization under electron irradiation were 180 K and 80 K, showing that the substitution of Cr for Fe in the sublattice had a marked effect on the annealing characteristics of the material. The low temperature dose to amorphization was higher in ZrFe₂ than in ZrCr₂ by a factor of two. The presence of a high density of stacking faults had a strong effect on amorphization in both compounds causing the critical temperature to be increased by 10-15 K. By contrast, the addition of Ni to Zr₃(Fe_1-x,Ni_x) had no effect on amorphization behavior for x=0.1 and 0.5. These results are discussed in terms of current models of amorphization based on defect accumulation and the attainment of a critical damage level, such as given by the Lindemann criterion.