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

Abstract

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 microhardness 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.