Ti80 strengthened by laser melt injection of Ni-coated SiC particles

Composite layers of Ti80 reinforced with SiCp and Ni-coated SiCp were prepared using laser melt injection (LMI). The effect of pre-Ni coating on SiCp was investigated in terms of the microstructural characteristics and mechanical properties of the resulting LMI layers. The results showed that the initially irregular SiCp, characterized by sharp edges, transformed into more rounded morphologies and exhibited numerous fine protrusions on their surfaces, with an average Ni-P coating thickness of approximately 2.875 μm after the electroless nickel plating process. Interface defects and a mixed TiC/Ti5Si3 reaction layer were observed in the LMI SiC/Ti80 layer. The pre-Ni coating on SiCp improved the wettability between the SiCp and the molten Ti80 alloy, resulting in defect-free interfaces and continuous TiC cellular reaction layers in the LMI Ni-coated SiC/Ti80 layer. This layer inhibited the continuous dissolution of SiCp into the Ti80 melt, allowing the injected SiCp to be retained to the greatest extent possible. Additionally, this SiCp pretreatment increased the surface hardness of the LMI SiC/Ti80 layer by 6.8% and reduced the wear rate per unit load and distance by 5.1%. The high interfacial bonding strength and the larger residual SiCp in the LMI Ni-coated SiC/Ti80 layer delayed the peeling of residual SiCp, leading to improved wear resistance compared to the LMI SiC/Ti80 layer. The wear behavior of the Ti80 substrate is predominantly governed by adhesive wear mechanisms, supplemented by oxidation and abrasive wear processes. Conversely, the LMI layers primarily experience abrasive wear, accompanied by simultaneous oxidation and adhesive wear phenomena.