Accession Number : ADA330972

Title :   Nonequilibrium Alloying of Aluminum for Improving the Corrosion Resistance of Graphite-Reinforced Metal Matrix Composites,

Corporate Author : PENNSYLVANIA STATE UNIV UNIVERSITY PARK

Personal Author(s) : Shaw, Barbara A. ; Schrecengost, Tia R. ; Miller, Paul L. ; Wendt, Robert G. ; Moshier, William C.

PDF Url : ADA330972

Report Date : JUN 1994

Pagination or Media Count : 15

Abstract : High modulus graphite (Gr) reinforced metal matrix composites (MMCs) offer a wide variety of attractive properties including: high specific modulus and strength (E/p and UTS/p), tailorable or zero coefficient of thermal expansion (CTE), and high thermal conductivity. Using Al as the matrix metal results in a reduction of the final density of the composite with high elastic modulus and excellent strength in the fiber direction. Unfortunately, MMCs, especially Gr reinforced composites, are extremely susceptible to corrosion with severe attack in chloride-containing environments occurring in as little time as several weeks for Gr/Al composites. The overall objective of this research is to determine whether improving the inherent passivity of the matrix metal in a Gr/Al composite can alleviate, or at least minimize, galvanic corrosion between the graphite and the matrix metal. This galvanic corrosion is currently the limiting factor in utilization of these composites. Our research focuses on the unique properties of sputter deposited alloys. With sputter deposition it is possible to significantly increase the solubility of passivity enhancing species, thus dramatically improving their corrosion resistance. The approach being undertaken is to develop alloy systems capable of minimizing galvanic degradation of the composite. An essential step in this process is identification of alloy compositions which maintain enhanced passivity after processing into the bulk composite. Our earlier work indicated that Al-Mo alloys provide the best combination of thermal stability, corrosion resistance, and alloy density. This paper will address the thermal stability and corrosion resistance of selected compositions of Al-Mo and Al-Mg-Mo alloys.

Descriptors :   *THERMAL STABILITY, *CORROSION RESISTANCE, *CARBON REINFORCED COMPOSITES, ALUMINUM ALLOYS, MODULUS OF ELASTICITY, METAL MATRIX COMPOSITES, THERMAL CONDUCTIVITY, SPUTTERING, MOLYBDENUM ALLOYS, GALVANIC CORROSION.

Subject Categories : Laminates and Composite Materials
      Properties of Metals and Alloys
      Thermodynamics

Distribution Statement : APPROVED FOR PUBLIC RELEASE