University of Florida Research Foundation Inc

Michael J Kaufman

S Jayashankar

Kyung-Tae Hong

A method for shaping a consolidated, substantially oxygen-free, equiaxed MoSi.sub.2 /SiC composite body having an average grain size of 10 .mu.m or less, a SiC content of 2 to 60 v/o and relatively low strength and relatively high ductility comprising subjecting the composite body to plastic deformation under conditions of forming temperature and rate of deformation such that grain growth is substantially avoided, the MoSi.sub.2 /SiC composite body being obtained by providing particles of molybdenum, silicon and carbon in a proportion relative to each other required to produce a composite powder of MoSi.sub.2 and SiC having a composition in that segment of the ternary diagram of FIG. 1 designated A, and subjecting the particles to mechanical alloying under conditions and for a time sufficient to produce the composite powder, followed by consolidation of the composite powder.

Method of manufacture of low O.sub.2 content MoSi.sub.2 /SiC composite

A method of producing a composite powder by providing particles of (I) tungsten, niobium, zirconium, titanium or mixtures thereof, (II) silicon and (III) carbon in a proportion relative to each other so as to possess an overall chemical composition in that segment of the ternary diagram of FIGS. 2(a), 2(b), 2(c) and 2(d) designated A, and subjecting the particles to a mechanical alloying process under conditions and for a time sufficient to produce the composite powder. Also disclosed is a method of forming a substantially oxygen-free composition of matter comprising a matrix substance of WSi.sub.2, NbSi.sub.2, ZrSi.sub.2, TiSi.sub.2 or alloys thereof having SiC dispersed therein, the method comprising consolidating the above-described composite powder. Also disclosed is a method of forming oxidation- and wear-resistant coatings by subjecting the composite powder whose composition lies in segment A to a metallurgical process such as plasma spraying. A method of forming a composite material of uniformly dispersed particles of silicon carbide in a silicide or an alloy silicide matrix is also disclosed. The matrix contains alloy silicides such as (Mo,W)Si.sub.2. The volume fraction of the silicon carbide may be varied from 10-90%. A method is also disclosed for producing hybrid composites consisting of a third phase of fibers or whiskers dispersed among a silicide/silicon carbide two-phase microstructure derived from the composite powder.

Composite silicide/silicon carbide mechanical alloy

A method of producing a composite powder by providing particles of, e.g., molybdenum, silicon and carbon, in a proportion relative to each other so as to possess an overall chemical composition in that segment of the ternary diagram of FIG. 1 designated A, and subjecting the particles to a mechanical alloying process under conditions and for a time sufficient to produce the composite powder. Also disclosed is a method of forming a substantially silica-free composition of matter comprising a matrix substance of MoSi.sub.2 having SiC dispersed therein, the method comprising consolidating the above-described composite powder. Also disclosed is a method of forming oxidation- and wear-resistant coatings by subjecting the composite powder whose composition lies in segment A to a metallurgical process such as plasma spraying. A method of forming a composite material of uniformly dispersed particles of silicon carbide in a silicide or an alloy silicide matrix, particularly molybdenum disilicide, is also disclosed. The matrix contains alloy silicides such as (Mo,W)Si.sub.2. The volume fraction of the silicon carbide may be varied from 10-90%. A method is also disclosed for producing hybrid composites consisting of a third phase of fibers or whiskers dispersed among a silicide/silicon carbide two-phase microstructure derived from the composite powder.

A method for producing a substantially silica-free composition of matter comprising a matrix of MoSi.sub.2 having SiC dispersed therein, the matrix being reinforced with a particulate ductile refractory metal, the method comprising providing a composite of the particulate ductile refractory metal and a substantially silica-free composite mechanical alloy powder comprising MoSi.sub.2 and SiC having a composition in that segment of the ternary diagram of FIG. 1 designated A, and consolidating the composite of particulate ductile refractory metal and mechanical alloy powder; the coefficient of thermal expansion of the MoSi.sub.2 matrix having SiC dispersed therein being substantially equivalent to that of the particulate ductile refractory metal. The composition of matter formed by the method and an article of manufacture comprising the same are also disclosed.

Growing community of inventors

Gainesville, FL, United States of America

Michael J Kaufman