Preparation of MoSi[sub 2]/SiC composites from elemental powders by reactive co-synthesis

Journal Article · Tue Jun 15 04:00:00 EDT 1993 · Scripta Metallurgica et Materialia; (United States)

DOI:https://doi.org/10.1016/0956-716X(93)90586-H· OSTI ID:6541293

Alman, D E; Stoloff, N S ^[1]

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1. Rensselaer Polytechnic Inst., Troy, NY (United States)

The intermetallic compound MoSi[sub 2] has potential for use as an elevated temperature structural material. Desirable properties include high melting temperature (2030[degree]C), low density (6.25 g/cm[sup 3]) and excellent oxidation resistance. However, the fracture toughness of MoSi[sub 2] is about 3 to 5 MPa[radical]m and the elevated temperature strength of MoSi[sub 2] is inadequate. The addition of SiC as particles or whiskers has improved the elevated temperature strength and creep resistance of MoSi[sub 2]. The fracture toughness of MoSi[sub 2] reinforced with SiC whiskers has been reported to be 8.2 MPa[radical]m. Thus, MoSi[sub 2]/SiC is emerging as a promising high temperature composite. It was first reported in the late 1940's and early 1950's that MoSi[sub 2] could be synthesized by the direct reaction of elemental Mo and Si powders (9). This technique involves intimately mixing elemental powders to stoichiometric proportions. The reaction is initiated between the powders by either externally heating the mixture (9) or by passing current through an electrode that was buried in the mixture (10). The reaction product is commonly milled into prealloyed powder. The reaction is exothermic in nature due to the high thermal stability of the forming intermetallic compound. As a consequence, heat is liberated and the reaction becomes self-sustaining and self-propagating. This type of materials synthesis approach has been described variously in the literature as self-propagating high-temperature synthesis (SHS), combustion synthesis or reactive synthesis. SiC is among the many compounds, besides MoSi[sub 2], that have been produced by the SHS technique (13-15). This research effort was undertaken in an attempt to synthesize MoSi[sub 2]/Si[sub C] composites in situ from elemental Mo, Si and C powders using a SHS type reaction that the authors have named reactive co-synthesis.

• OSTI ID: 6541293
• Journal Information: Scripta Metallurgica et Materialia; (United States), Journal Name: Scripta Metallurgica et Materialia; (United States) Vol. 28:12; ISSN SCRMEX; ISSN 0956-716X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360601* -- Other Materials-- Preparation & Manufacture
ALLOYS
CARBIDES
CARBON COMPOUNDS
COHERENT SCATTERING
COMPOSITE MATERIALS
DATA
DIFFRACTION
EXPERIMENTAL DATA
FABRICATION
INFORMATION
INTERMETALLIC COMPOUNDS
MATERIALS
MOLYBDENUM ALLOYS
NUMERICAL DATA
POWDERS
SCATTERING
SILICON ALLOYS
SILICON CARBIDES
SILICON COMPOUNDS
SYNTHESIS
X-RAY DIFFRACTION