Al bonding in air by inserted A5056 was investigated in this study. Heating rate in thermal history of bonding process may have the relation with the growth of Al oxide film and the deformation of bonding surface by softening. Both of phenomena affect the joinability and the mechanical properties of bond. Al bonding in air was carried out by several heating rate. Growth of Al oxide film significantly suppressed the progress of bonding in air by low heating rate, 1K/s. Decrease of deformation of bonding surface suppressed also the progress of bonding by high heating rate, 10K/s. In case of medium heating rate, 5K/s, good joinabilty of Al bonding in air was obtained by the medium growth of oxide film and the deformation of bonding surface.