No it isn't.
Here is how it can be devalued: the government says all bonds issued before date x must be traded in for a new series issued date y with a couple of zeros chopped off the coupon. Bonds not traded in become valueless.
Since all Treasury bonds are electronic now, that would be very simple.
But that would be defaulting on the debt, not devaluing the currency.
It wouldn't be defaulting on the debt. It would be repaying the debt with a devalued currency. Paid in full.
IIRC Turkey actually did revalue their currency the same way a number of years ago. Recall issued currency and replace it with smaller denominated currency.