Effect of laser power variation on microstructure and properties of selective laser melting coating deposited on TC4 titanium alloy.

Abstract

The surface properties of aviation titanium alloy directly affect its service safety and reliability, and high-performance coating are essential for its practical application. However, existing studies lack clear guidance on laser power parameters for preparing high-quality TiAl coating on titanium alloy substrates, leaving a research gap in optimizing coating quality and performance. To fill this gap, this work used selective laser melting (SLM) to fabricate TiAl coating on titanium alloy substrates, focusing on the influence of laser power (350-380 W) on coating microstructure, phase composition, elemental distribution and microhardness. SEM, XRD and EDS characterizations were used for systematic analysis. The results show that laser power is the key factor determining coating quality. Severe longitudinal cracks appeared at 350 W and 360 W, leading to poor interfacial bonding and potential coating peeling. The optimal laser power was 370 W, achieving good metallurgical bonding without obvious defects. New Ti5Al11 and Al2Sc phases were formed with a controlled Al/Ti weight ratio of 1:1.8, and the coating reached the highest microhardness of 641.9 HV0.2. Excessively high power (380 W) caused numerous cracks and reduced coating performance. This research provides certain technical references and theoretical support for the preparation of TiAl coating on the surface of aerospace titanium alloys.