Creep behavior of an Al-6061 metal matrix composite reinforced with alumina particulates

Journal Article · Sat Nov 01 04:00:00 EST 1997 · Acta Materialia

DOI:https://doi.org/10.1016/S1359-6454(97)00132-8· OSTI ID:590030

Li, Y; Langdon, T G ^[1]

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1. Univ. of Southern California, Los Angeles, CA (United States)

Creep tests were conducted on an Al-6061 matrix alloy reinforced with 20 vol.% of irregularly shaped Al{sub 2}O{sub 3} particulates. The composite was fabricated using an ingot metallurgy technique and the creep properties were determined at temperatures from 623 to 773 K. The results show high values for both the apparent stress exponent (up to >10) and the apparent activation energy for creep ({approximately}200--275 kJ/mol) but it is demonstrated, by incorporating a threshold stress into the analysis, that the true stress exponent is close to 3 and the true activation energy is close to the value for diffusion of Mg in the Al matrix. The results suggest that creep is controlled by the viscous glide of dislocations in the Al-6061 matrix alloy. Very fast creep rates are observed at the highest stress levels owing to the breakaway of dislocations from their solute atom atmospheres. Direct comparison shows that the creep resistance of this composite is less than in an Al-6061 alloy reinforced with 20 vol.% of Al{sub 2}O{sub 3} microspheres. This difference is attributed to the creation of additional precipitates in the microsphere-reinforced composite because of an interfacial reaction between the matrix alloy and the reinforcement.

• Sponsoring Organization: Department of the Army, Washington, DC (United States)
• OSTI ID: 590030
• Journal Information: Acta Materialia, Journal Name: Acta Materialia Journal Issue: 11 Vol. 45; ISSN 1359-6454; ISSN ACMAFD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
ALUMINIUM OXIDES
COMPOSITE MATERIALS
CREEP
DISLOCATIONS
REINFORCED MATERIALS