"In a previous study on Cr-Cr3Si in-situ composites, samples were arc melted1. A yield strength of 359 MPa at 1200°C was reported for an alloy of 25% Cr and 75% Cr3Si. This strength, as well as the low temperature strength and toughness need to be enhanced for use in high temperature gas turbine engine applications. In this study, two approaches were taken to improve the strength and toughness of the Cr-Cr3Si in-situ composite at low and elevated temperatures. These two approaches were powder metallurgy and dispersion strengthening. Powder metallurgy was used to produce a more equiaxed microstructure than was observed in the arc melted alloys in an attempt to improve both strength and toughness. The other approach, dispersion strengthening, used erbia as a dispersoid to improve the elevated temperature strength.
Samples of Cr-15.5Si with erbia were produced by arc melting. High density samples of Cr-15.5Si and Cr-18.6Si were produced by hot pressing chromium and chromium silicide powders in a graphite die. These samples were made with and without erbia for comparison purposes.
Four-point bend and Vickers microhardness testing were performed to evaluate the mechanical properties of the alloys. The microhardness indentations were also used to evaluate the toughness. Optical and electron microscopy was used to characterize the microstructures. The properties of the alloys were affected by hot pressing and the erbia. The erbia also aided in the consolidation of the hot-pressed samples. A Cr-15.5Si alloy with erbia was produced with a density 98% of theoretical"-Abstract p. iii
Joseph W. Newkirk
Donald R. Askeland
Lokeswarappa R. Dharani
Materials Science and Engineering
M.S. in Metallurgical Engineering
University of Missouri--Rolla
ix, 67 pages
© 1995 Joseph Edward Price, All rights reserved.
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Price, Joseph E., "Processing of dispersion strengthened chromium-silicon alloys" (1995). Masters Theses. 1427.
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