Alloying and cladding treatments have been performed on pure aluminium and a 5%Si-3% Cu-Mg A1-based alloy by an electron beam technique. Metal sheets of Ti-6A1-4V alloy and pure nickel were used for cladding and alloying respectively. In both cases the sheets were mechanically clamped on the substrate. In the cladding process, a thin layer of substrate only a few tens of microns thick was affected by the melting process. In the alloying process, melting and solidification of the Ni overlayer with a controlled amount of substrate lead to a significant modification of the surface microstructure and microhardness.