| abstract |
Chemical milling of cast superalloys having high tungsten contents is advantageously accomplished with an etchant which consists by volume percent of 40-60 concentrated HNO3, 0.6-0.8 concentrated HF, 30-70 H2O, with which is included at least 0.008 moles/liter CuSO4 and 0.0016-0.025 moles/liter FeCl3. Preferably the molar ratio of CuSO4 to FeCl3 is 2:1 and etching is accomplished in the range 50 DEG -80 DEG C. |