  We present a systematic study of $^{6}$Li elastic scattering and total
reaction cross sections at incident energies around the Coulomb barrier within
the continuum discretized coupled-channels (CDCC) framework, where $^{6}$Li is
treated in an $\alpha$+$d$ two-body model. Collisions with $^{27}$Al,
$^{64}$Zn, $^{138}$Ba and $^{208}$Pa are analyzed. The microscopic optical
potentials (MOP) based on Skyrme nucleon-nucleon interaction for $\alpha$ and
$d$ are adopted in CDCC calculations and satisfactory agreement with the
experimental data is obtained without any adjustment on MOPs. For comparison,
the $\alpha$ and $d$ global phenomenological optical potentials (GOP) are also
used in CDCC analysis and a reduction no less than 50$\%$ on the surface
imaginary part of deuteron GOP is required for describing the data. In all
cases, the $^6$Li breakup effect is significant and provides repulsive
correction to the folding model potential. The reduction on the surface
imaginary part of GOP of deuteron reveals a strong suppression of the reaction
probability of deuteron as a component of $^{6}$Li as compared with that of a
free deuteron. A further investigation is made by taking the $d$ breakup
process into account equivalently within the dynamic polarization potential
approach and it shows that $d$ behaves like a tightly bound nucleus in $^{6}$Li
induced reactions.
