I have a Ti64 specimen that has given me only two-phase structure with metallography and fine-grained. What needs to be done to determine the boundaries?
Grind, polish and etch with Kroll's reagent to look at the microstructure perhaps? Could also try using electron backscatter diffraction.
Dear Afsane,
I recommend to go for electron backscatter diffraction (EBSD) specially for fine grain.
Hi,
For Ti6Al4V, the Kroll’s etchant etches beta phases, revealing dark color under optical microscope. So it does not etch the boundaries of alpha phase. If you don’t have an access to EBSD, still metallography would be a good alternative for your purpose. If you are interested in determining grain size, somewhat you can estimate it by image analysis of your captured images. Since beta phase normally appears in alpha boundaries (for equiaxed microstructure), you can approximately determine grain size of both phases by image analysis. If your grains are ultra-fine which can not be clearly seen by optical microscope, again you can do etching then use SEM. By using SEM in high magnifications, you probably will be able to observe the alpha grain interfaces (since not all alpha grains are etched the same, there will be a contrast between the adjacent grains). Afterward, you can utilize your SEM images for image analysis in a more accurate way.
Best regards,
Masoud
Do you see no effect of etching with Kroll's? How long and how did you etch your specimen? Have you polished your specimen enough before etching? You might want to try using Keller's reagent if Kroll's does not work very well. According to some researchers claim that Keller's (although used mainly for aluminium) works well some times.
Hi,
I used Keller's for Ti5553, which is a near beta alloy, and it worked. I'm quite sure that you can use Keller's for Ti64 as well. I've seen people using Keller's for this alloy. You should be able to see grain boundaries. Good luck!
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