Dutile intermetallic toughened carbide matrix composites
- Oak Ridge National Lab., TN (United States); and others
Ductile nickel aluminide (Ni{sub 3}Al) alloys have been used as a `binder` phase for the fabrication of both titanium and tungsten carbide (TiC and WC) matrix composites. Ni{sub 3}Al alloys are also unusual in that their yield strength increases with temperature, to a maximum at 700-800{degrees}C. These properties, combined with high tensile ductilities (up to 50% strain), make Ni{sub 3}Al a potentially attractive replacement for Co in cemented carbide fabrication. Materials have been fabricated by both hot-pressing and vacuum-sintering, with Ni{sub 3}Al contents ranging from 15 to 95 vol. %. Vacuum-sintering cycles were generally similar to those used for the fabrication of WC/Co and TiC/Ni (i.e. T{sub sint} {approximately}1450-1600{degrees}C), resulting in sintered densities >95 % of theoretical. WC/Ni{sub 3}Al materials exhibited an order of magnitude improvement in corrosion resistance over WC/Co, during immersion tests in either sulfuric or nitric acid. These materials also demonstrated improved high temperature strength retention compared to WC/Co cermets, though the initial room temperature strengths were lower. Fracture toughness varied between 8 and 25 MPa m{sup {1/2}}, and depended primarily upon Ni{sub 3}Al content and composition.
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 567541
- Report Number(s):
- CONF-960106--
- Country of Publication:
- United States
- Language:
- English
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