الفهرس 
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Abstract
Titanium alloys are widely used in aerospace, marine and chemical industries owing to their intrinsic properties such as high specific strength, excellent corrosion and oxidation resistance. However, because of their low hardness and poor tribological properties, the application of titanium alloys is severely constrained under severe wear and friction conditions. Laser cladding is a promising technique that is widely used to enhance the surface properties of many kinds of metals. Laser cladding process was performed on a commercial Ti-6Al-4V (α + β) titanium alloy by means of tungsten carbide-nickel based alloy powder blend. Nd:YAG laser with a 2.2-KW continuous wave was used with coaxial jet nozzle coupled with a standard powder feeding system. A deposition of a blended powder consisting of 60 wt % tungsten carbide (WC) and 40 wt % NiCrBSi was successfully made on the alloy. The high content of the hard WC particles is intended to enhance the abrasion resistance of the titanium alloy. The goal was to create a uniform distribution of hard WC particles that is crack-free and nonporous to enhance the wear resistance of such alloy. This was achieved by changing the laser cladding parameters to reach the optimum conditions for favorable mechanical properties. The obtained results revealed that the best clad layers were achieved at a specific heat input value of 59.5 J•mm−2. An increase by more than three folds in the microhardness values of the clad layers was achieved and the wear resistance was improved by values reaching 400 times. Based on such encouraging results, the study was continued in order to accomplish a larger clad layer thickness. Therefore a higher powder flow rate of 20 g.min-1 at the optimum specific heat input of 60 J.mm-2 was attempted. In addition, the influence of different laser interaction times on the properties of the obtained clad layer was studied. The coating so produced exhibits multiple hardness values and exceptional wear resistance under abrasion test conditions. The obtained results reveal good quality clad layer that was achieved at a laser interaction time of 0.3 s. An increase of more than four times in the microhardness values of the clad layers was achieved and the wear resistance was thus significantly enhanced.