Ni-Cu M-35-1/Monel alloy in investment casting can not pass the examination of gas pressure due to low compactness of microstructure resulting from the generation of CuO inclusion in grain

which is attributed to long time Cu smelting at high temperature resulting in the serious oxidation due to the high difference of melt point between Ni and Cu.Through adjusting material-adding sequence and deoxidized method

increasing deoxidized time to fully ensure deoxidization as well as shortening oxidized time of Cu at high temperature to reduce the oxidation of Cu

the problems can be effectively eliminated.The investment castings can totally meet the requirement by quality check with qualified rate more than 97% of gas pressure examination.