High temperature creep and oxidation resistant chromium silicide matrix alloy containing molybdenum
AssigneeThe United States of America as represented by the Administrator of the National Aeronautics and Space Administration
InventorSai V. Raj
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Abstract
Cr.sub.3 Si is alloyed with molybdenum which produces a two-phase microstructure of (Cr,Mo).sub.3 Si and (Cr,Mo).sub.5 Si.sub.3. About 50 weight percent of molybdenum is present in the alloy. The alloy forms two protective oxides over a wide range of temperatures. Chromium and molybdenum oxide volatize under flowing air at high temperatures above 1200.degree. C. which facilitates the formation of SiO.sub.2 on the surface. Below 1200.degree. C. Cr.sub.2 O.sub.3 is formed. The new alloy has excellent high temperature strength and creep properties.
Claims6
A Cr.sub.3 Si matrix alloy having improved high temperature creep strength and oxidation resistance at temperatures up to about 1400.degree. C. comprising
- about 20 wt % to about 80 wt % chromium,
- about 50 wt % molybdenum, and
- about 14.5 wt % to about 43 wt % silicon so that a two-phase microstructure of (Cr,Mo).sub.3 Si and (Cr,Mo).sub.5 Si.sub.3 is produced.
A method of improving the high temperature creep strength and oxidation resistance of a Cr.sub.3 Si alloy comprising alloying about 50 wt % molybdenum with said alloy to produce a two-phase microstructure of (Cr,Mo).sub.3 Si and (Cr,Mo).sub.5 Si.sub.3 so that Cr.sub.2 O.sub.3 is formed below about 1200.degree. C. and SiO.sub.3 is formed above about 1200.degree. C.
Dependencies are inferred from the claim text.