Effect of Microstructure on Microhardness and Electrochemical Behavior in Hypereutectic… DOI: http://dx.doi.org/10.5772/intechopen.81095

evolution, further, Cordovilla et al. [20] pointed out as essential tool to understand way in which each track affects the microstructures produced by previous one. On the other hand, Guan et al. [28] argued that overlapping is important in determining corrosion resistance due to microstructure in-homogeneities in the molten pool.

However, Kalita [1] noted existence of increase in corrosion resistance comes as a result of homogenization and microstructure refinement, which is due to the surface layer melting, as well as through decreases electrical conductivity of resultant passive layer, still these same authors argue, laser surface melting is a useful method for corrosion protection of friction stir weld surfaces as a result of improved microstructure and phase distribution. Nevertheless, Watkins et al. [19] reported, laser surface treatments offer significant potential for improvement of materials properties such as corrosion performance and wear resistance.

The authors Yue et al. [14] who reported, potentiodynamic polarization tests showed that as a result of laser treatment, the corrosion current can be reduced by as much as six times, and a passive region was obtained. Besides, analysis of electrochemical impedance measurements showed that at an open-circuit potential (OCP), the polarization resistance and double-layer capacitance of the film electrolyte interface of laser-treated specimen were one order of magnitude higher and six times lower than that untreated specimen, respectively.

Since then, hypereutectic Al-2.0 wt.% Fe alloy laser-treated is very peculiar and that it has very special characteristics. Therefore, in this study the influence of microstructural characteristic on microhardness and electrochemical behavior was demonstrated clearly, thus it has an innovative character and can be applied in aerospace, aeronautical and automobile industries. Guan et al. [28] argued, which overlapping adjacent traces as a result of multiple passes using scanning laser beam is usually adequate for production of area coverage. It has long been realized that laser beam overlapping may play a significant role in influencing final surface properties of laser-treated materials.
