Experimental investigations of Aluminium plates by doping of metals such as lead and zinc by solid state diffusion process before being joined by friction stir welded was carried out successfully. Same metal weld and work piece don't give the better strength at the welding point. So the alternative is made the metal alloy at the point of weld. With the help of alloy formation it gives the better strength as well as improves the properties of metal. Doping process will used to improve the properties of metal, so that weld bead gives the maximum strength. After carrying out number of trial experiments, it has been found that the aluminium sample doped with Pb (Lead) and welded with cylindrical tool profile gives the maximum value of micro hardness as well as tensile strength. However, there is reduction in values of micro hardness and tensile strength if the aluminium is doped with Zinc metal.