Patent ID: 9481934
Filing Date: 2016-11-01
CPC Classification: C23F,C23G

Claim Text:
1. A method of removing a work-affected layer, the method comprising: a step of dipping a TiAl-based alloy, having the work-affected layer having a thickness of 5 μm to 20 μm formed on a surface thereof by machining, in an etchant consisting of predetermined concentrations of hydrofluoric acid and nitric acid, wherein the dipping is performed under conditions in which an etching temperature is within a range of 20 to 40° C., an etching time is within a range of 10 to 30 minutes, and an etching rate is within a range of 1 to 15 μm/min, and wherein within the etchant, the concentration of the hydrofluoric acid is not less than 5 g/L and not more than 56 g/L, and the concentration of the nitric acid is selected from within a range from not less than 50 g/L to not more than 260 g/L in accordance with a combination of a concentration of the hydrofluoric acid within the etchant and an etching treatment temperature.