2.2 Laser surface treatment

In this research, Al-2.0 wt.% Fe alloy was subjected to laser surface remelting (LSR), without gas protection, with the purpose of generating metastable phases, using a 2 kW Yb-fiber laser (IPG YLR-2000S) in order to examine treated and untreated layers. LSR treatment was performed in a laboratory at Institute for Advanced Studies (IEAv) of Aerospace Technical Center (CTA–ITA) in São Jose dos Campos, SP, Brazil. A laser scanning speed of 40 mm s<sup>1</sup> was applied. Average

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


Table 1.

behavior was also observed by Kalita [1], who applied laser surface melting (LSM)

Pariona et al. [2, 3] used LSR technique in a study of hypoeutectic Al-1.5 wt.% Fe alloy. Characterization of the cast region revealed the formation of a refined, dense and highly homogeneous microstructure, as well as cracking, noticeably with a high formation of protuberance on the weld fillets than alloy untreated. An overlapping line of consecutive weld fillets was also perceptible in the cast region of this alloy, which resulted in an increase of about 61% in hardness compared to the base material. According to Pariona et al. [4], which the Marangoni effect influence thermal gradient in the molten pool a high temperature, meanwhile, also it produces effects in quality and properties of microstructure, morphological characteristic and as well as quality of laser-treated workpiece track. Yet these same authors confirmed, at low laser beam velocities, the morphology is higher and quality of

Moreover, Trdan and Grum [5] analyzed that laser shock peening (LSP) process

Hypereutectic Al-2.0 wt.% Fe alloy under study was prepared with commercially pure raw materials. The material was cast in a resistance furnace (muffle) by pouring the liquid metal into a cylindrical ingot mold and cooling in ascending mode. Resulting ingot was sectioned into various samples, which were sand blasted individually to determine the chemical composition of alloy by energy-dispersive X-ray fluorescence

In this research, Al-2.0 wt.% Fe alloy was subjected to laser surface remelting (LSR), without gas protection, with the purpose of generating metastable phases, using a 2 kW Yb-fiber laser (IPG YLR-2000S) in order to examine treated and untreated layers. LSR treatment was performed in a laboratory at Institute for Advanced Studies (IEAv) of Aerospace Technical Center (CTA–ITA) in São Jose dos Campos, SP, Brazil. A laser scanning speed of 40 mm s<sup>1</sup> was applied. Average

spectrometry (Shimadzu EDX-7000), as indicated in Table 1.

enables the improvement of corrosion resistance by means of increased pitting potential with lower intensity of pitting attack on the specimen's surface. Hatamleh et al. [6] confirmed higher corrosion resistance of laser-peened friction stir-welded 7075 aluminum joints in a 3.5% NaCl solution. Although, Pariona and Micene [7] and Pariona et al. [2] analyzed, which during LSR-treatment in Al alloy, the melted zone was constituted of metastable phases by LAXRD analysis and it revealed the presence mainly of Al2O3 and AlN phases. These authors emphasized, which these phases contributed in the microstructural modification, favored the characteristics of high hardness and corrosion resistance of LSR-treated workpiece in sulfuric acid. This study involved LSR treatment of hypereutectic Al-2.0 wt.% Fe alloy. The samples was characterized by various techniques, including optical microscopy (OM), scanning electron microscopy (SEM), Vickers microhardness test. Analysis of Vickers hardness were done in the cross-sectional area of treated sample and on the treated sample surface. Furthermore, the electrochemical impedance spectroscopy (EIS) test was studied and their numerical simulation was done. The microstructure microhardness and electrochemical behavior of laser-treated layer were systematically investigated to correlate their properties with process involved.

technique in a study of high strength aluminum alloys (HSAL).

Aerospace Engineering

track presents many defects than at high laser beam velocities.

2. Materials and methods

2.2 Laser surface treatment

2.1 Material

176

Chemical composition of materials used for manufacture of Al-2.0 wt.% Fe alloy.

power of the laser beam was set at 600 W and the power density on the sample surface was estimated at 4.8 <sup>10</sup><sup>5</sup> W cm<sup>2</sup> . Laser-treated samples were covered with several weld fillets during the remelting process [8].
