Abstract
M.Ing. (Mechanical Engineering)
The aim of this research project is to investigate the effect of laser deposited hybrid coatings (Al-Cu-Fe) on the physical, mechanical and metallurgical properties of titanium alloy (Ti-6Al-4V) by experimental techniques and numerical analysis. Laser Additive Manufacturing is relatively new in the manufacturing industry. Laser metal deposition (LMD) can be used to manufacture freeform shapes, to produce parts from graded porous to fully dense solid structures as well as to directly create various surface coatings on a part. This investigation also enhances the mechanical and corrosion properties of hybrid coatings of Al-Cu-Fe on Ti-6Al-4V alloy applicable in the aerospace industry through LMD technique. Icosahedral Al-Cu-Fe as quasicrystals are a relatively new class of materials which exhibit unusual atomic structure with useful physical and chemical properties. Ti6Al4V/Al-Cu-Fe composites were analysed using optical microscopy, scanning electron microscopy (SEM) with energy dispersive microscopy (EDS), indentation testing, x-ray diffraction (XRD) analysis. The hardness and wear resistance performances of the laser coatings were examined by high diamond dura scan microhardness tester and CERT UMT-2 reciprocating sliding machine. The anti-corrosion performances were evaluated by linear polarization technique in 3.5 M NaCl. It was found that the geometrical properties (deposit width and height, heat affected zone (HAZ) height), dilution rate, aspect ratio and powder efficiency of each sample remarkably increased with increasing laser power due to the laser-material interaction. However, the geometrical properties decrease with increasing scanning speed. Solidification began with formation of some large particles such as Al and Fe. The atomic migration of Cu into Ti lattice resulted in the formation of β-Ti phase during cooling and travels a longer distance in the Ti lattice than other elements which opens more crystallographic structure of the β matrix. It was observed that there was higher number of titanium and aluminium presented in the composite as per the theoretical expectation. The indentation testing reveals that Ti6Al4V/Al-Cu-5Fe composite has the highest mean hardness value and it decreases with increasing laser power at scanning speed of 0.8 m/min and 1 m/min. The corrosion and wear resistance of titanium alloy was improved by depositing Al-Cu-Fe quasicrystalline coating. The results obtained from numerical simulation using CFD analysis demonstrated that Ti6Al4V/Al-Cu-10Fe has the highest dilution rate, aspect ratio and HAZ height, and this corresponded with the experimental results. Finally, it was found that Ti6Al4V/Al-Cu-Fe composite have useful mechanical, physical and...