A model for the creep of tantalum at elevated temperature has been presented in which the increase in strain rate with strain is related to the reduction of .the cross-sectional area accompanying strain. Comparison of experimental data with the proposed theory indicates that the dominant creep mechanism beyond the second stage of creep starts at a point of highest temperature or at a stress concentration, spreads throughout the volume in the immediate vicinity, and eventually results in localized "necking down."
Uhrig, Robert E., "A proposed model for high temperature creep of tantalum" (1960). Ames Laboratory Technical Reports. 21.