A Tantalum Lock Nut is essentially used when there is a significant probability that a nut may loosen over time due to frequent temperature changes, vibrations and torque.
Tantalum Lock Nuts are also commonly known as a locking nut, prevailing torque nut, stiff nut or elastic stop nut. Elastic stop nuts and prevailing torque nuts are of the particular type where some portion of the nut deforms elastically to provide locking action.