Hello, everyone
This is biaobiao.
In recent days, I have tried to do EBSD at the FIB milled surface. Well, using a 30 kV Ga+ ion beam, and ion beam currents ranging from 40 pA to 790 pA, I still cannot see the Kikuchi lines.
I also tried to adjust the EBSD capture parameters like exposure time and binning modes low as 1×1, unfortunately, I still cannot see the Kikuchi lines. Of course, no indexing.
The Ga+ influenced depth, in my view, should be around 10-20 nm. Well, the EBSD detects the information of depth as 10 nm, I guess. Is that meaning, I will not get the EBSD after FIB milling?
If anyone has successfully performed FIB-EBSD on Mg, pls. give me your suggestion or experience.
That's it.
Thanks a lot.
Best wishes,
This experiment should be really helpful to figure out the grain boundary (GB) characteristics like GB inclination angle to calculate the Lee–Robertson–Birnbaum (LRB) parameter. I will try lower voltages, if I get any progress, I will let you know.
It should be possible. They do (HR-)EBSD on FIB milled Mg in this paper: Article {10-12} twinning mechanism during in situ micro-tensile load...
Tijmen Vermeij Glad for your share. It's one of the most amazing jobs, that I have reached recently. But now, I feel more puzzled, because they are using FIB slicing parameters of 30 kV and 500 pA. As I have said in the question description, under the ion current ranging from 790 pA to 40 pA, I cannot see any Kikuchi patterns. Now, I don't know how they completed EBSD using these parameters.
If you know more details about preparing 3D EBSD in that work, pls. tell me.
Hi Biaobiao! We performed many EBSD mapping on Mg pillars/tensile bars produced by FIB. You have to be extra careful with the preparation and evade any unnecessary FIB scanning on your sample. Use another part for focusing; image only the parts that are essential for positioning your FIB tool. Otherwise the image quality will degrade quite fast. It could also be a redeposited layer that masks your Kikuchi patters. Good luck!
Szilvia Kalácska I am very happy to receive your reply since you are one of the authors of the work we mentioned above.
We know the influence of ion beam, so we always use another part for focusing.
And you mentioned another possible factor, the redeposited layer, that may mask my Kikuchi patterns. I am not sure about it, is there any feasible way to detect or remove it?
If possible, could you provide more details about your FIB-EBSD, like pattern mode, etc.
At the last, thanks for your time and consideration!
Biaobiao
I am thinking about the geometrical relationship between the ion beam direction and surface, which may influence the redeposited layer. Now, I am using a direct perpendicular ion beam on the surface.
The EBSD information depth should be (depending of course on many parameters) about 100 nm or so (unless you are doing TKD). The FIB damaged layer in case of proper preparation should be way less, as you mentioned. So you could detect diffraction patterns. There could be tons of other reasons why you can't see Kikuchi lines, but I don't know for example what camera are you using or what is the material that you are investigating. In case of redeposition, usually a last step of cleaning ("polishing" or "cleaning cross section" tool) should solve the issue. In the supplementary file of this (Article Evolution of deformation twinning mechanisms in magnesium fr...
) article it is described how our pillars were prepared. It can also be an issue of your specific Mg-alloy: FIB irradiation might induce a phase transformation (it happens i.e. in some steels). For EBSD measurement you could try to apply an electron beam of 30kV and high current (>10nA) (increasing the information depth) just to see if you can detect any Kikuchi lines. You could also try broad beam Ar ion polishing first to remove larger volumes of damaged surface layer, and start FIB milling on that surface (see more here:Article EBSD sample preparation: high energy Ar ion milling
).
... and you ion beam milling is supposed to be parallel to the surface you are preparing.
I have tried to use a low Voltage ion beam. Now, under the conditions of 5 kV, 40 pA Ga ion beam parameters, 30 kV, 5.4 nA, and 200 ms EBSD parameters, we can get the EBSD maps finnally, as you can find it in the attachment.
Szilvia Kalácska And the ion beam milling direction should have influenced the Ga+ ion irradiated depth greatly. The 90-degree vertical FIB, possibly, severely damages the surface. Thanks for your constructive advice.
Best wishes,
Biaobiao
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