WC nano-particle implanting strengthening on aluminum alloy surface via laser shock peening

We have developed a novel process: nano powder implanting via laser shock peening process, by which the nano powders are squeezed into the surface layer of light metal alloys by the very high pressure (up to giga pascals) induced by the laser shock peening process. Laser shock peening hardens the material surface by the laser-induced shock wave and the residual compressive stress, it is typically a cold process, which is capable of avoiding the defects like the melting loss of the lower-melting-point elements, porosity, cracking and surface deterioration associated with a conventional thermal hardening approaches of aluminum alloys. This also eliminates the problem when hardening a material with nanoparticles, that is, the easy melting of nano particles in a melt pool and then solidified a microstructure without nano characteristics. This paper reports the work on nano WC powder implanting onto aluminium alloy surface by laser shock peening, focusing on the process development, parameter influence, microstructure, hardness, residual stress and wear resistance. The research approves that after implanting of WC nano particles by laser shock peening, the surface hardness of aluminum alloy is enhanced by 20%, wear resistance increases 5 times than that of original aluminum and 1.5 times than that of the only laser shock peened surface. The surface tensile state of aluminum alloy is changed to be beneficial compressive state at the same time.