Microstructure and properties of Al{sub 2}O{sub 3}/Al composites formed by in situ reaction of aluminum and mullite

Conference · Tue Aug 01 04:00:00 EDT 1995

OSTI ID:77979

Ewsuk, K G; Glass, S J; Loehman, R E ^[1]; Fahrenholtz, W G ^[2]; Ellerby, D T ^[3]

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1. Sandia National Labs., Albuquerque, NM (United States)
2. Univ. of New Mexico, Albuquerque, NM (United States)
3. Univ. of Washington, Seattle, WA (United States)

Novel property Al{sub 2}O{sub 3}/Al composites have been produced by reactive metal penetration, which includes in situ reaction of molten Al with dense mullite ceramic performs. Molten aluminum reduces mullite to produce alumina and elemental silicon following the reaction, 3 Al{sub 6}Si{sub 2}O{sub 13} + (8 + x) Al {r_arrow} 13 Al{sub 2}O{sub 3} + (x) Al + (6 {minus} y) Si {minus} (y) Si{sub (lost to melt)}. Si diffusion out of the system produces an Al{sub 2}O{sub 3}/Al composite containing up to 30% by volume Al. Al{sub 2}O{sub 3}/Al composites produced by in situ reaction of aluminum and mullite have improved physical properties relative to the dense mullite ceramic perform. A rigid alumina skeleton dominates composite physical properties such as Young`s modulus (E), hardness (Hv), and coefficient of thermal expansion (CTE), while the interpenetrating ductile Al metal phase contributes to improved composite fracture toughness (K{sub IC}). Composite K{sub IC} increases with increasing metal content, x, and microstructural analysis of fracture surfaces of metal-ceramic composites produced by reactive metal penetration show visible evidence of the ductile metal failure.

• Research Organization: Sandia National Laboratory
• DOE Contract Number: AC04-94AL85000
• OSTI ID: 77979
• Report Number(s): CONF-950201--; ISBN 0-87339-283-3
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM
ALUMINIUM OXIDES
COMPOSITE MATERIALS
FRACTURE PROPERTIES
HARDNESS
LIQUID METALS
MICROSTRUCTURE
MULLITE
PHYSICAL PROPERTIES
SYNTHESIS
THERMAL EXPANSION
YOUNG MODULUS