The simultaneous investigation of Li and Be in stars is a powerful tool in the study of the evolutionary mixing processes .
Here , we present beryllium abundances in stars along the whole evolutionary sequence of the open cluster IC 4651 .
This cluster has a metallicity of [ Fe/H ] = +0.11 and an age of 1.2 or 1.7 Gyr .
Abundances have been determined from high-resolution , high signal-to-noise UVES spectra using spectrum synthesis and model atmospheres .
Lithium abundances for the same stars were determined in a previous work .
Confirming previous results , we find that the Li dip is also a Be dip .
For post-main-sequence stars , the Be dilution starts earlier within the Hertzsprung gap than expected from classical predictions , as does the Li dilution .
Theoretical hydrodynamical models are able to reproduce well all the observed features .