Creep mechanism of highly purified V-4Cr-4Ti alloys during thermal creep in a vacuum

Pressurized thermal creep tubes of highly purified V-4Cr-4Ti, the NIFS-Heat2 alloy have been examined following testing in the range 700 to 850degC. It was found that the creep stress exponent of the NIFS-Heat2 alloy is about 5 and that the characteristic creep mechanism was the dislocation creep usually observed in pure metals. The apparent activation energy of creep deformation is about 210kJ/mol in the temperature range 700 to 850degC. Creep deformation was considered to be controlled by climb-controlled dislocation glide at 850degC, where sub-grain boundary structure predominates and consists of dislocation dipole structures and pile-ups of dislocations. (author)