Influence of microstructure on the strength of Nicalon-reinforced aluminium metal-matrix composites

• Published in: Journal of materials science Vol. 29; no. 17; pp. 4523 - 4534
• Main Authors: CHAPMAN, A. R, BLEAY, S. M, SCOTT, V. D
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer 01.09.1994
• Subjects: Applied sciences; Exact sciences and technology; Fibre reinforced metals; Metals. Metallurgy; Powder metallurgy. Composite materials; Production techniques; Aluminium base alloys; Silicon carbide; Fibre reinforced metal; Silicon alloy; Mechanical properties; Fracture surface; Interface reaction; Microstructure; Composite material
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/BF00376275

The microstructure and mechanical properties of two aluminium-based composites reinforced with Nicalon fibre were investigated. During composite processing, aluminium carbide forms at the interface as a result of a reaction between aluminium and free carbon in the fibre. Magnesium, when present in the aluminium matrix, diffuses into the outer (about 200 nm) layer of the fibre where it reacts with the silicon oxycarbide constituent to form magnesium-containing oxide and also to free carbon for the production of more interfacial aluminium carbide. These chemical reactions affect the strength of a fibre to differing degrees, as measured after extraction from the two composites, and influence the respective fibre/matrix interfacial friction stress and composite strength. A simple rule-of-mixtures approach based upon the measured strength of extracted fibres gave some agreement with longitudinal properties of the composite, but treatment of the fibres as bundles, using a Weibull probability distribution of properties, provided more accurate predictions. 19 refs.