Accession Number : ADA289851

Title :   Evaluation of the Oxidation Response and Fiber-Matrix Compatibility in Aluminum-Rich Intermetallic Composites.

Descriptive Note : Final rept. Oct 89-Sep 93,

Corporate Author : NAVAL AIR WARFARE CENTER AIRCRAFT DIV WARMINSTER PA AIR VEHICLE AND CREW SYST EMS TECHNOLOGY DEPT

Personal Author(s) : Frazier, William E. ; Cook, Jeffrey ; Mickle, Thu-Ha T.

PDF Url : ADA289851

Report Date : 17 NOV 1993

Pagination or Media Count : 83

Abstract : The present study was undertaken in order to elucidate the role of fiber-matrix interactions on the oxidation response of Al3Ti-based metal matrix composites. The fibers examined in this work were SCS-6, TiB2, and Saphikon. Since these trialuminides have very high melting points, a solid state powder processing fabrication route was chosen in order to minimize fiber degradation. The matrix alloy was rapidly solidified by melt spinning in order to insure compositional homogeneity. A hammer mill was used to comminute the alloy ribbon into -40 mesh powder. The powder and fibers were then encapsulated in titanium cans, hot vacuum degassed, and hot isostatically pressed. Preliminary investigations indicated that Al3Ti's narrow range of compositional stability could present difficulties: excess aluminum could melt and vigorously attack fibers at the HIP consolidation temperatures. viz., 1100 deg C and 1200 deg C. Niobium additions were used to expand the phase field of Al3Ti and reduce the alloy's propensity to partition aluminum during melt processing. HIP consolidated composites all exhibited some matrix cracking making them unsuitable for oxidation studies. However. the oxidation response of the monolithic matrix alloys was investigated. The extent of fiber-matrix reaction owing to the HIP consolidation procedure was also pursued. The SCS-6 fibers reacted severely with the matrix materials. The TiB2 fibers did not experience significant chemical degradation although significant diffusion and cracking was observed. Saphikon was the least affected by the consolidation process. The fiber does not react chemically with the matrix materials; however, differences in the thermal expansivities of the fiber and matrix materials are believed responsible for extensive cracking. (jg)

Descriptors :   *FIBERS, *COMPOSITE MATERIALS, *MATRIX MATERIALS, *OXIDATION, *ALUMINUM, *INTERMETALLIC COMPOUNDS, TEST AND EVALUATION, OPTICS, STABILITY, DEGRADATION, INTERACTIONS, THERMODYNAMICS, POWDERS, PROCESSING, HIGH TEMPERATURE, CRACKS, X RAY DIFFRACTION, VACUUM, MELTS, COMPATIBILITY, SOLIDIFICATION, ALLOYS, MESH, BRITTLENESS, SPINNING(INDUSTRIAL PROCESSES), RESPONSE, NIOBIUM, ADDITIVES, CONTAINERS, TITANIUM, MONOLITHIC STRUCTURES(ELECTRONICS), BORON, MELTING POINT, METALLOGRAPHY, HOMOGENEITY, COMPOSITION(PROPERTY), CHEMICAL ATTACK(DEGRADATION), ALUMINIDES.

Subject Categories : Inorganic Chemistry
      Physical Chemistry
      Metallurgy and Metallography

Distribution Statement : APPROVED FOR PUBLIC RELEASE