High-temperature creep of pure platinum

Geep behavior has been investigated with high purity platinum (99.999 mass%) at high temperatures from 1373K up to 1773K. Stress and temperature dependance of the creep rate has been discussed in detail by using microscopic observations and X-Ray diffraction measurements. Platinum shows the power-law creep with the stress exponent of the steady state rate of about 6. Recrystallization to bamboo-type gains from the initial polycrystalline micro-grains has been observed In these specimens a strain burst (a sudden increase in the strain) has been detected. The occurrence of this burst depends on the concentration and kinds of minute impurities, test-temperature, applied stress, and the detailed process of the specimen preparation. The fracture mode changes from the void coalescence to the necking or shearing-off by the recrystallization The activation energy for the steady state creep is (3.1 +/- 0.3) x 10(5) J/mol.