[en] Highlights: • A better understanding of the nitride layer formed on titanium alloy. • Search for titanium treated with high wear-resistance and low cost. • Crack-free nitride layer was formed by the GTAW method. - Abstract: In this investigation, titanium nitride (TiN) reinforcements are synthesized in situ on the surface of Ti–6Al–4V substrates with gas tungsten arc welding (GTAW) process by different methods to add nitrogen, nitrogen gas or TiN powder, to titanium alloys. The results showed that if nitrogen gas was added to titanium alloys, the TiN phase would be formed. But if TiN powder was added to titanium alloys, TiN + TiN_x dual phases would be presented. The results of the dry sliding wear test revealed that the wear performance of the Ti–6Al–4V alloy specimen coated with TiN or TiN + TiN_x clad layers were much better than that of the pure Ti–6Al–4V alloy specimen. Furthermore, the evolution of the microstructure during cooling was elucidated and the relationship among the wear behavior of the clad layer, microstructures, and microhardness was determined

[en] Highlights: ► Solidification process of the SiC clad layer is investigated and discussed. ► Microhardness distribution and wear mechanism of SiC clad layers are discussed. ► Complex structure and graphite clearly affected wear resistance of SiC clad layers. - Abstract: In this research, the metastable phases, such as Fe₃C and Fe₈Si₂C, were synthesized in situ during a cladding process with gas tungsten arc welding (GTAW), which used silicon carbide (SiC) powder to clad on an SKD61 die steel substrate. According to the nanoindentation test and microstructure observation, these metastable phases displayed hard and complex geometric structures in the SiC clad layer. Moreover, because the SiC clad layer contained a large amount of Si and C elements, it was easy to promote graphite precipitation during solidification. During sliding, the hard and complex microstructure in the SiC clad layer caused the mechanical interlocking effect, so that the worn surface would be difficult to result in the serious adhesion and plastic deformation. Furthermore, because the graphite distributed over the worn surfaces, it could provide good lubricity. Under the dry sliding wear test, the wear performance of an SKD61 die steel specimen with the SiC clad layer was much better than that of an SKD61 die steel specimen, and even better than that of an SKD61 die steel specimen with the WC clad layer