  We investigate {\alpha}-decay half-lives for 74 {\le} Z {\le} 92 even-even
nuclei within the semiclassical WKB approximation in deformed relativistic
Hartree-Bogoliubov theory in continuum (DRHBc). The {\alpha}-particle
preformation factors are estimated from cluster-formation model using both
empirical AME2020 binding energies and numerical ones obtained by a deep neural
network (DNN) study in which available DRHBc binding energies are used as
training set. We find that our estimated {\alpha}-decay half-lives are
qualitatively in agree with experimental results. We also compare our results
with the empirical formulae, ZZCW and UNIV. Based on these observation, we
extend our predictions of {\alpha}-decay half-lives for the isotopes whose
experimental data are not available.
