MICROSTRUCTURE PERFORMANCE OF La2O3-MODIFIED TUNGSTEN INERT GAS CLAD COMPOSITE COATING

摘要

A hard coating free of obvious defects is produced on a Ti-6Al-4V (TC4) alloy substrate by means of tungsten inert gas clad (TIGC) of the Deloro22-WC-La2O3 mixed powders, which greatly increased the surface performance of the substrate. Test results indicated that large quantities of needle-shape precipitates were formed in the Deloro22-WC TIGC coating, increasing the micro-hardness significantly, and also lots of pores are produced in this coating, weakening the wear resistance. It was noted that a fine/compact microstructure is obtained in the Deloro22-WC-La2O3 TIGC coating, also the defects cannot be observed obviously. La2O3 addition can effectively improve the fluidity of melt and hinder the growth of grains in TIGC pool, favoring a fine/compact microstructure to be produced, and also improving the wear property of the TIGC coating.