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Pt-20Rh dispersion strengthened by ZrO2 particles in different volume fractions has been produced by consolidation of milled powder which has been internally oxidized. The microstructure has been characterized by scanning electron microscopy, electron backscatter diffraction, and transmission electron microscopy; tensile properties have been determined at RT and 1000 °C. The Pt-20Rh matrix is subdivided on the submicrometer scale by low angle dislocation boundaries and high angle boundaries. ZrO2 particles with sizes in the range 5–35 nm are uniformly distributed and with increasing volume fraction the flow stress increases and at 0.9% it is doubled both at RT and at 1000 °C. Based on the superposition of particle and matrix strengthening, the flow stress has been calculated and good accord has been found with experiment both at RT and 1000 °C.
Bibliographical noteGA no. 788567
- Dispersion strengthening
- Orowan stress
- Internal oxidation-powder metallurgy