Friction Stir Welding of aluminium based composites reinforced with a L2O3 particles: effects on microstructure and charpy impact energy

Abstract

The aim of the present research was to study the effect of the Friction Stir Welding process on the microstructure and impact toughness of the composites W6A20A (AA6061 reinforced with 20vol.% of Al2O3 particles) and W7A10A (AA7005 reinforced with 10vol.% of Al2O3 particles). FSW, because of the concurrent effect of severe plastic deformation and frictional heating during welding, had effects both on the reinforcing particles and the aluminium matrix. It induced a significant reduction in the reinforcement particles size and their better distribution in the welded zone as well as a grain refinement of the aluminium alloy matrix in the nugget due to dynamic recrystalizzation. The frictional heating, moreover, had effects on the growth, dissolution and re-precipitation of hardening precipitates. The impact tests showed that the total impact energies increased in the FSW composites, respect to the corresponding base materials.