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 tempera ture dependance of the creep rate has been discussed in detail by usin g microscopic observations and X-Ray diffraction measurements. Platinu m shows the power-law creep with the stress exponent of the steady sta te rate of about 6. Recrystallization to bamboo-type gains from the in itial polycrystalline micro-grains has been observed In these specimen s 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 t he void coalescence to the necking or shearing-off by the recrystalliz ation The activation energy for the steady state creep is (3.1 +/- 0.3 ) x 10(5) J/mol.