Boron-implantation-induced crystalline-to-amorphous transition in nickel: An experimental assessment of the generalized Lindemann melting criterion

The generalized Lindemann melting hypothesis has recently been used to develop a unified thermodynamic criterion for melting applicable to both heat-induced melting and disorder-induced crystalline-to-amorphous (c-a) transformation. The hypothesis stipulates that the sum [mu(2)](Total) of the static and dynamic root-mean-square (rms) atomic displacements is a constant fraction of the nearest-neighbor distance along the melting curve of a solid. To test this hypothesis, energy-filtered selected area electron-diffraction intensity measurements were used to determine the generalized Lindemann parameter delta= root[mu(2)](Total) /d(nn), in which d(nn) represents the nearest-neighbor distance, as a function of boron concentration during implantation of 50-keV B+ into polycrystalline Ni at 77 K. The onset of amorphization was found to occur close to 10 at. % boron, which is in good agreement with the value predicted by T-o curve calculated using the generalized Lindemann hypothesis. Moreover, the critical value of the generalized Lindemann parameter for amorphization, delta(Critical) =0.115+/-0.01, is within experimental error, identical to that for Ni just below its thermodynamic melting temperature of T=1728 K, hence providing a direct confirmation for the generalized Lindemann melting hypothesis.