A novel Ti cored wire developed for wire-feed arc deposition of TiB/Ti composite coating

摘要

A novel Ti cored wire containing Ti B2,Al60 V40 and Ti6 Al4 V mixed powders was developed for wirefeed arc deposition of Ti B/Ti composite coating,to enhance the hardness and wear resistance of Ti alloy.Results showed that after experiencing several chemical reactions,the wire was melted in the arc zone and turned into nonuniform droplets composed of Ti-Al-V-B melt and undecomposed Ti B2 particles.With the increase of welding current,the detachment time of droplet shortened while the transfer frequency accelerated,accompanied by the improvement in coating surface quality.The spatial distribution of Ti B whiskers in coating was governed by welding current.A uniform distribution could be achieved as welding current was sufficient at the expense of elevated dilution ratio,while increasing wire feeding speed could compensate the dilution loss of Ti B whisker to some extent.The decomposition process of Ti B_(2)particles and the microstructure evolution mechanism of coating was discussed in detail.The optimum coating possessed uniform microstructure,relatively low dilution ratio,and high hardness(639.1 HV_(0.5))as compared with Ti6 Al4 V substrate(326 HV_(0.5)).Indentation morphology analysis verified the excellent performance was ascribed to the load-sharing strengthening of Ti B whiskers.This study provides a high-efficiency fabrication method for the ever-developing titanium matrix composites(TMCs)coating.