  The quasi-fission mechanism hinders fusion of heavy systems because of a mass
flow between the reactants, leading to a re-separation of more symmetric
fragments in the exit channel. A good understanding of the competition between
fusion and quasi-fission mechanisms is expected to be of great help to optimize
the formation and study of heavy and superheavy nuclei. Quantum microscopic
models, such as the time-dependent Hartree-Fock approach, allow for a treatment
of all degrees of freedom associated to the dynamics of each nucleon. This
provides a description of the complex reaction mechanisms, such as
quasi-fission, with no parameter adjusted on reaction mechanisms. In
particular, the role of the deformation and orientation of a heavy target, as
well as the entrance channel magicity and isospin are investigated with
theoretical and experimental approaches.
