The Effects of Laser Remelting on the Microstructure and Mechanical Properties of WC-TiC Reinforced TiNi-Ti2Ni Dualphase Intermetallic Matrix Coatings
X. Luo, J. LI and G.J. LI
WC-TiC reinforced TiNi-Ti2Ni dual-phase intermetallic matrix coatings were fabricated on the Ti6Al4V substrate by laser alloying with 70 pure Ni and 30 WC powders (wt.%) and then were dealt with by laser remelting. The effects of laser remelting on microstructure of the alloyed coatings were investigated by X-ray diffraction (XRD), optical microscopy (OM), scanning electron microscopy (SEM) coupled with energy dispersive spectrometry (EDS). In addition, mechanical properties were also evaluated. The results indicated that the remelted coating became denser with the reduction in defects compared with the alloyed coating. The average microhardness of the coating had few changes after remelting, however, the fracture toughness of the coating was increased significantly by 20% to 3.15 MPa·m1/2. Moreover, wear volume and mass loss of the coating before and after laser remelting also showed that laser remelting contributed to the improvement in wear performance.
Keywords: CO2 laser, Ti6Al4V, TiNi-Ti2Ni dual-phase, intermetallic, composite coating, laser alloying, laser remelting, defects, microstructure, microhardness, fracture toughness, wear resistance