Tribological Performance of Ni₃Al Matrix Composites Synthesized by Laser Melt Deposition Under Different Scanning Velocities

In order to study the effect of scanning velocity on the microstructure and tribological properties of Ni₃Al matrix composites containing graphene nanoplatelets (NGs), a series of NG samples are successfully synthesized by laser melt deposition under the various scanning velocities from 300 to 500 mm s⁻¹. The sliding friction tests of NG against GCr15 steel balls are carried out under 10 N and 0.2 m s⁻¹ at room temperature. The microstructures, tribological properties and wear mechanisms of the NG samples are analyzed. The results show that the scanning velocity can be optimized to effectively control the surface hardness and relative density, as well as tribological performance of NG. The NG sample synthesized under scanning velocity of 450 mm s⁻¹ has a dense and fine microstructure as well as excellent properties such as higher relative density (98.6%), lower friction coefficient (0.23) and wear rate (5.5 × 10⁻⁶ mm³ N⁻¹ m⁻¹). The lower substrate layer with dense and stable structure plays an important role in supporting the upper glaze layer with rich graphene and oxides, as well as nanocrystalline structure, which contributes to the excellent friction-reducing and wear resistance performances of NG. The research results could be used to guide the selection of suitable scanning velocity and study the wear mechanisms of NG for having excellent tribological performance.