  We estimate the non-perturbative power-suppressed corrections to heavy
flavour fragmentation and correlation functions in e^+e^- annihilation, using a
model based on the analysis of one-loop Feynman graphs containing a massive
gluon. This approach corresponds to the study of infrared renormalons in the
large-n_f limit of QCD, or to the assumption of an infrared-finite effective
coupling at low scales. We find that the leading corrections to the heavy quark
fragmentation function are of order $\lambda/M$, where $\lambda$ is a typical
hadronic scale ($\lambda\sim 0.4$ GeV) and M is the heavy quark mass. The
inclusion of higher corrections corresponds to convolution with a universal
function of M(1-x) concentrated at values of its argument of order $\lambda$,
in agreement with intuitive expectations. On the other hand, corrections to
heavy quark correlations are very small, of the order of $(\lambda/Q)^p$, where
Q is the centre-of-mass energy and $p \ge 2$.
