The Impact of Zn and Cu Reinforcements on Microstructural Enhancement and Performance of Laser Cladded Ti-Zn-Cu/Ti-6Al-4V Composite Coatings

Abstract

The effects of zinc and copper reinforcements on Titanium alloy via Direct Laser Metal Deposition (DLMD) process was investigated. Process parameters had great influence on the microstructure, metallurgical evolution, tensile and yield strengths performance. The process parameters had a significant influence on these factors considered, including the morphology of the surface, density, hardness, evolution of the microstructure, accuracy of the fabricated coatings dimensions and the mechanical performance of the Titanium alloy components processed by DLMD. The results of the investigation showed that the hardness had increased in proportion to the increase of the processing laser power coupled with the increase velocity of the laser scan. Moreover, for a laser power equivalent to and exceeding 1000 W, the hardness became less susceptible to the laser power. Morphological observations along the side of the surface showed the prominence of the adhesive powder, flow path of the melt pool and the areas which overlapped, attributed to the increase of the laser scanning speed. When the laser scanning speed was increased it attributed to the grain width reduction of the prior beta and a transformation in shape of the martensitic primary alpha into fine needle-like structures. In terms of the yield and tensile performance, the results revealed that increasing the scan velocity was favourable to the property, showing that the mechanical performance became better at higher scanning speeds. At the set laser intensity of 1000 W and a 1.0 m/min laser scanning speed, the fabricated coatings enhanced with 48.03 % hardness, 47.42 % tensile strength and 29.81% yield strength.