Method of detecting contamination of titanium alloys of two-phase type having an alpha and a beta phase
A method of examining a titanium alloy with an alpha phase and a beta phase is disclosed. The method includes: cutting a sample of a part made of the alloy; preparing a region of the cut surface of the sample situated in the vicinity of the edge of the sample, the edge being in common with the outside surface of the part; observing the alpha phase of the region at a magnification of greater than ×5000; deciding on whether granularity is present or absent in the alpha phase of a first zone contiguous with the edge of the sample; and concluding that the alloy has been contaminated with a gas if granularity is found to be absent in the alpha phase of the contiguous zone whereas granularity is present in the alpha phase outside the contiguous zone.
1. A method of examining a titanium alloy, the method comprising:
a) cutting a sample of a part comprising a titanium alloy of two-phase, having an alpha phase and a beta phase, to obtain a cut surface;
b) preparing a region of the cut surface that is located in a vicinity of an edge of the sample, the edge being in common with an outside surface of the part;
c) observing the alpha phase of the region at a magnification of greater than ×5000;
d) deciding whether granularity is present or absent in the alpha phase of a first zone contiguous with the edge of the sample; and
e) concluding that the alloy has been contaminated with a gas if granularity is absent in the alpha phase of the first zone and granularity is present in the alpha phase outside the first zone.
2. The method of claim 1 , wherein the observing is performed with a scanning electron microscope.
3. The method of claim 1 , wherein the preparing comprises polishing the region and then chemically etching the region with at least one reagent.
4. The method of claim 3 , wherein the chemical etching is performed using a single reagent.
5. The method of claim 4 , wherein the reagent is a 0.5% aqueous solution of hydrofluoric acid.
6. The method of claim 2 , wherein the preparing comprises polishing the region and then chemically etching the region with at least one reagent.
7. The method of claim 6 , wherein the chemical etching is performed using a single reagent.
8. The method of claim 7 , wherein the reagent is a 0.5% aqueous solution of hydrofluoric acid.
9. The method of claim 3 , wherein the polishing is specular polishing.
10. The method of claim 6 , wherein the polishing is specular polishing.
11. The method of claim 3 , wherein the at least one reagent comprises a 0.5% aqueous solution of hydrofluoric acid.
12. The method of claim 6 , wherein the at least one reagent comprises a 0.5% aqueous solution of hydrofluoric acid.
13. The method of claim 3 , wherein the chemical etching is performed for a duration of 15 to 30 seconds.
14. The method of claim 6 , wherein the chemical etching is performed for a duration of 15 to 30 seconds.
15. The method of claim 5 , wherein the chemical etching is performed for a duration of 15 to 30 seconds.
16. The method of claim 8 , wherein the chemical etching is performed for a duration of 15 to 30 seconds.
17. The method of claim 1 , wherein the observing is at a magnification of greater than ×10,000.
18. The method of claim 2 , wherein the observing is at a magnification of greater than ×10,000.
19. The method of claim 5 , wherein the observing is at a magnification of greater than ×10,000.
20. The method of claim 8 , wherein the observing is at a magnification of greater than ×10,000.