No, nothing becomes brittle. This was a problem way back when DCT was being developed. The problem was the cool down of the object subjected to the cryogen was happening way too quickly. We all probably remember the experiments we did in HS with LN2 where one would stick a rose in LN2 and then you could shatter it. That is why the temp. must be brought down very gradually, or damage could easily occur.
Brittleness was an issue with "thermal shock", a by-product of not being able to control the rate at which things cooled down. Being as we are in the age of the computer (and really cool solenoid controlled valves), this is simply not an issue anymore if proper procedures are followed.
I haven't found anything yet that cannot be treated, but I'm sure I will someday. Pantyhose last longer, razors last longer, golf balls fly farther, etc...
I will bring some Bic razors (that have been DCT) to the GPAF for members here. You'll have to ask for them so I know who you are, but you will be amazed at how long they last. Perhaps someone could write a review on the fine quality shave they received!
Regards,
Lee