Effect of trace O element on the high-temperature wettability between Ni3Al scrap melt and Y2O3 ceramic at 1873 K is investigated.With the increase in O content in Ni3Al scrap melt from 6 to 21 ppm,the equilibrium contact angledecreases from 93.3° to 88.9°.The initial surface tension and adhesive work of molten Ni3Al scrap drop from 3153.5 to 807.4 mN m-1 and from 2974.6 to 882.2 mN m-1,respectively.The average spreading rate increases from 0.03° s-1 to 0.17° s-1.The whole wetting processes are divided into four periods.The main driving force for spreading in period (1) is the adsorption and diffusion of active atoms around the interface.Trace O content in Ni3A1 scrap has a significant impact on interfacial reactions which mostly take place in the second stage,and can accelerate the spreading process on Y2O3 substrate.The reaction products during wetting process are Y3Al5O12,YAlO3 and Al2O3.