Refractory metals dispersion-strengthened

Space technology has always demanded materials that can operate at temperatures between those of superaHoys and refractory metals and that have high temperature strength during operation and room temperature ductility for fabrication. The development of dispersion-strengthened and oxide alloy systems has solved part of this problem. 

Initially refractory metals were applied mainly in the pure state. Extensive developments mainly driven by US aerospace programs led to a wide variety of alloys now commercially available. The compositions of solid-solution, precipitation- and dispersion-strengthened alloys are given in Table 3.1-108. Tungsten heavy metals and refractory-metal-based composite materials are not included here. 

There is extensive evidence that between 300 and 500 °C, oxide-dispersion-strengthened (ODS) refractory metal alloys (e.g.. Mo—LaaOs and Mo—Y2O3 grades) possess markedly reduced oxidation rates compared to the pure metals [1.133]. In-situ oxidation and evaluation of the binding state reveal that M0O2 dominates over M0O3 both for Mo and Mo-... 

The generalized BE approach also finds application in the P/M processing of composite materials for high-temperature service— i.e., the term could be applied to the introduction of oxide particles or unconstitutional precipitates (e.g., refractory intermetallic compounds) as dispersion strengtheners, or of suitably coated SiC or refractory metallic whiskers for fiber reinforcement. 

Chen, Y, Wu, Y. C., Yu, F. W, Chen, J. L. (2008). Microstructure and mechanical properties of tungsten composites co-strengthened by dispersed TiC and LUjOj particles. International Journal of Refractory Metals and Hard Materials, 26, 525-529. doi 10.1016/j.ijrmhm.2007.12.004. 

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