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Industrial applications require parts of components with specific surface properties such are good corrosion resistance, wear resistance and hardness. Alloys with those properties are usually very expensive and there is a great interest in reducing the cost of components for fulfilling these requirements. In this sense, laser surface processing has been used as a cost-effective technique to improve the surface properties of materials, by use of the laser beam heat for modification of its structure and physical characteristics. Laser surface treatments can be divided into direct processes, which only need the generated heat, such are hardening and melting, and processes which need filler material as alloying and cladding. Therefore, the aim of this paper is to summarize the results of several works based on laser surface treatments, in particular, hardening and melting of hot and cold work steels, and laser cladding of forming tools with nanoparticles. The microstructural characterization and mechanical properties (microhardness, wear resistance) will be described in each case.

Friction stir processing (FSP) is a promising technique for improving plasticity of magnesium alloys through the homogenization and grain refinement of their structure. In this study, a magnesium alloy AZ31 has been processed by FSP to achieve an ultrafine grain size structure (700 nm), and the oxide films formed spontaneously on the surface of the FSP zone are compared with those on the unprocessed material. Chemical composition of the oxide films are analyzed by XPS.The natural oxide films, close to 36 nm, can be described as a structure of (MgO)/Mg(OH) 2 with the outermost surface mainly formed by Mg(OH) 2 /MgCO 3 . About 5-7 at.% of Al 3+ is distributed through the oxide layer. Segregated zinc enrichment (Zn 2p 3/2 at 1021.4 eV) at the interface oxide/metal is found. The FSP samples show higher carbonatation degree at the surface and a lower segregated zinc percentage at the interface oxide/metal.

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