Canada's etchant - Nickel superalloys

Canada's etchant - Nickel superalloys

Material Name: Nickel superalloys
Recipe No.: 12068
Primary Chemical Element in Material: Ni
Sample Type: Bulk
Uses: Macrostructure
Etchant Name: Canada's etchant
Type (Macro/Micro): Macro
Etching Method: Chemical
Etchant (Electrolyte) Composition: 8 parts H2O, 2 parts H2SO4, 2 parts HF, 1 part H2O2 (35% wt.%)
Procedure (Condition): Slice and etchant are both to be hotter than 70°C. Remove slice when piece darkens (no set time of exposure). Rinse and dry.
Note: This etchant also was stable, though extra operating precautions were required because of the temperature and HF acid content. The squares responded quickly to Canada's, clearly revealing dendritic pattern and black spots within about ten minutes. Canada's etch performed reliably and reproducibly, though at the cost of some added precautions for users who are not accustomed to working with hot solutions containing HF acid. It was very comparable in response to the HCl Electrolytic etch regarding interdendritic segregation.
Reference: T. Le Roux and D.A. Wells, AN ASSESSMENT AND COMPARISON OF TEE SENSITIVITY OF VARIOUS MACROETCHES FOR ALLOY 718, Superalloy 718-Metallurgy and Applications, Edited by E.A. Loria, The Minerals, Metals & Materials Society, 1989, pp. 109-118.