Modified SNECMA "Dark Etch" etchant - Nickel superalloys

Material Name: Nickel superalloys
Recipe No.: 12072
Primary Chemical Element in Material: Ni
Sample Type: Bulk
Uses: Macrostructure
Etchant Name: Modified SNECMA "Dark Etch" etchant
Type (Macro/Micro): Macro
Etching Method: Chemical
Etchant (Electrolyte) Composition: 8 parts FeCl3, 1 part conc. HCl, 1 part H2O
Procedure (Condition): Preheat the slice. Immerse in etchant at nominal 60°C. Remove after ~20 minutes and rinse. Dry with blown air.
Note: A modified SNECMA "Dark Etch" was used only on the strip section sample. It defined very little of the interdendritic segregation. There were evidently no white spots available for it to highlight.
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.













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