LASER-SURFACE ALLOYING OF ALUMINUM TRANSITION-METAL ALLOYS

Laser surface alloying has been used as a tool to produce hard and cor rosion resistant Al-transition metal (TM) alloys. Cr and Mo are partic ularly interesting alloying elements to produce stable high-strength a lloys because they present low diffusion coefficients and solid solubi lity in Al. To produce AI-TM surface alloys a two-step laser process w as developed: firstly, the material is alloyed using low scanning spee d and secondly, the microstructure is modified by a refinement step. T his process was used in the production of AI-Cr, AI-Mo and AI-Nb surfa ce alloys by alloying Cr, Mo or Nb powder into an Al and 7175 Al alloy substrate using a CO2 laser. This paper presents a review of the work that has been developed at Institute Superior Tecnico on laser alloyi ng of AI-TM alloys, over the last years.