Application to tracer diffusion in Zr Ni and Ti Ni shows that 10 or fewer matrix atoms may be involved, and the size effect of diffusing atoms on Q agrees with experimental measurements.
where A is the dimensionless parameter, G is the shear modulus, ε is the lattice strain due to the size difference between solute and matrix atoms, C is the concentration of solute atoms.
The activation energy Q depends on the bond strengths, size of diffusing atoms, the elasticity of the matrix and the effective number of the involved matrix atoms.
The actual state of the precipitate is described by its effective radius and by the thickness of the layer of the matrix atoms deposited at the precipitate/matrix interface.
…case they are known as substitutional elements), or, if they are appreciably smaller than the matrix atoms, they may take up places between regular sites (where they are called interstitial elements).
The atoms of the alloying metals may substitute for matrix atoms on regular sites (in which case they are known as substitutional elements), or, if they are appreciably smaller than the matrix atoms, they may take up places between regular sites (where they are called interstitial elements).
At steady state, the incorporation of incident atoms does not change the ratio of surface concentrations for matrix atoms.
However, this results in the inclusion of a shell of matrix atoms, which must be removed through an erosion step, to define the final cluster.
In the case of H+ irradiation, on the other hand, electronic excitation and hydrogen accumulation in the matrix with some chemical bonding to the matrix atoms significantly affected the damaging rate, the effects of which were semi-quantitatively extracted.
