Effect of microstructure on mechanical properties and fracture of dispersion strengthened platinum

Two types of dispersion strengthened Pt with the same weight fraction (0.5%) of Y sub 2 O sub 3 particles are analyzed in the paper. But the technological parameters of their preparation by application of laboratory manufacture procedure are different. The first material (A) has worse strength and plastic properties in the temperature interval from 20 to 600 deg C. At the temperature 600 deg C their properties are similar to the properties of pure Pt metal. Second material (B) has very favourable strength properties up to the temperature of 700 deg C. They are two-three times better than those of the material (A) and they also exceed the strength parameters of dispersion strengthened Pt materials used at present. In this paper the essence of different properties of both materials on the qualitative level is explained on the basis of microstructural and microfractografical analyses. Better properties of the material (B) consist in grain refining of Pt matrix, low porosity and its stability, higher effectiveness of dispersion strengthening, in thermomechanical effect and with it connected increase of dislocation strengthening.