# Platinum as a Metallic Material

## Oxide Dispersion Hardened Platinum Materials

It has been known since the 1960s that the creep strength of metals at high temperatures (approx. > 0.7 Tm) can be substantially increased by introducing finely dispersed particles of a thermodynamically stable oxide into the microstructure. This can simultaneously reduce the tendency to grain growth in the structure. The phenomenon is referred to as oxide dispersion hardening or strengthening.

Example

Examples are nickel and iron alloys hardened with thoria, ThO2, or yttria, Y2O3, or aluminum hardened with alumina, Al2O3.

Oxide dispersion hardening is also applied to a large variety of platinum materials, and is marketed by Heraeus under the designation DPH. The most important materials have the compositions of chemically pure platinum, PtRh95/5, PtRh90/10, PtAu95/5 together with a wide variety of platinum-iridium, platinum-tungsten and other variants. The most commonly used dispersoids are zirconia, ZrO2 - either pure or doped with yttria, Y2O3, and scandia, Sc2O3. These materials have a much higher strength than the conventional, non-dispersion hardened materials at high temperatures and show better corrosion resistance as a result of the reduced grain growth.

Fig.1
PtRh90/10 after exposure 30 h at 1,600 $°C$
Fig.2
PtRh90/10 DPH after exposure 30 h at 1,600 $°C$
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