In the case of Inconel 718 this utilised Kallings No.
2 reagent (2 g CuCl + 40 ml hydrochloric acid + 60 ml of 95%
ethanol) and for Ti–6Al–4V, used Kroll’s reagent (2% hydrofluoric
acid + 10% nitric acid + 88% water). Microstructural analysis was
carried on a Leica DM LM microscope with selected samples
evaluated using scanning electron microscopy (SEM).