Influence of scanning speed on the microstructure of deposited Al-Cu-Fe coatings on a titanium alloy substrate by laser metal deposition process

Abstract

Laser Additive Manufacturing is relatively new in the manufacturing industry. This paper focuses on the influence of scanning speed on Al-Cu-Fe coating powders on a titanium alloy using laser metal deposition (LMD) process. Al-Cu-Fe as quasicrystals are a relatively new class of materials which exhibit unusual atomic structure and useful physical and chemical properties. The intermetallic section where the hybrid coating bonded into grade five titanium alloy substrate were observed. It was found that the geometrical properties of the deposits such as deposit width, deposit height and the Heat Affected Zone (HAZ) of each sample decreases with increasing scanning speed due to the laser-material interaction. It was observed that an increase in scanning speed results in an increase in both dilution and aspect ratio. However, this is not true for the graph of powder efficiency as a function of scanning speed, increasing scanning speed decreases the powder efficiency. The smoother surface observed at low scanning speed that is as a result of proper melting of Ti powder due to the large laser material interaction time. As the scanning speed increases, the laser material interaction time reduces causing more and more unmelted Ti powder to be seen. The mean hardness value decreases with increasing scanning speed. XRD analysis showed that increasing scanning speed will significantly increase the diffraction peak of Ti and Ti3Al.