In-situ TiB2-TiC reinforced Fe-Al composite coating on 6061 aluminum alloy by laser surface modification

Abstract To improve the wear resistance of 6061 aluminum alloy, we have reported the fabrication of in-situ TiB2-TiC reinforced Fe-Al composite coatings by laser alloying with Fe-based self-fluxing alloy, B4C and Ti mixed powder. Two Ti contents, which are 30 wt. % and 45 wt. %, in the alloyed coatings were investigated as comparisons, so that investigate phase compositions, microstructures and wear resistance of the alloyed coatings. Additionally, the disregistry between (0001)TiB2 and (111)TiC planes were calculated, of which the formation mechanism of TiB2/TiC composite structure was further analyzed. It was found that the alloyed coatings mainly consisted of TiB2, TiC, Fe4Al13, Cr2B, Cr7C3, Al3Ti and α-Al. With the addition of 30 wt. % Ti, we found that TiC nucleated heterogeneously on the surface of short rod-like TiB2, forming TiB2/TiC composites. The interface was well bonded with a low disregistry of 1.049 %. The average micro-hardness of the composite coating was larger than 7 times of the substrate with a high value of 520 HV0.2. Moreover, a 92.8 % reduction in the volume loss enunciated a significant enhancement in wear resistance. Nevertheless, with the increase of Ti component in the alloyed coating, the supportability of the metal matrix to the reinforcements decreased, resulting in a slight reduction of the micro-hardness and wear resistance.