The significance of a correlation of blister diameter with skin thickness for Ni and Be for blistering models

It has been suggested that large lateral stresses introduced in an ion implanted surface layer may cause elastic instability and buckling of the implant layer (blister formation), and result in a relationship Dsub(mp) proportional to tsup(3/2) between the most probable blister diameter Dsub(mp) and the blister skin thickness, t, for metals such as Be, V, stainless steel, Nb and Mo. To test this relationship a systematic study of the correlation between blister diameter and skin thickness for helium blistering of annealed polycrystalline Ni and Be has been conducted for helium ion energies in the range of 15-300 keV. For beryllium the relationship between Dsup(mp) (μm) and t(μm) can be fitted by the expression Dsub(mp)=24.6tsup(1.25) whereas for nickel a best fit is obtained for the expression Dsub(mp)=1.24tsup(1.5). These results, together with earlier results for Nb and V show that the relationship between Dsub(mp) and t is stronly dependent on the type of metal studied and do not support the lateral stress model for blister formation. (Auth.)