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Abstract

The fracture surfaces of AT-400 (Al-Al₂O₃, SAP-type) dispersion-strengthened alloy specimens, broken in impact over the temperature range 20 to–170°C, have been examined visually and by electron microscopy. Test temperature, dispersed-particle morphology, grain size, and method of alloy fabrication all affected the mode of fracture.

Conventional fabrication of aluminium SAP-type alloys appears to lead to grain-boundary porosity associated with reduced ductility. Specimens fabricated using a vacuum annealing treatment before final consolidation have more ductility than specimens of commercial-purity aluminium.

The presence of the grain-boundary porosity, coupled with the fine Al₂O₃ dispersion, can produce independently nucleated microcleavage facets in the aluminium matrix. The appearance of this type of fracture is very similar to that observed for dispersion-strengthened non-metallic crystalline materials.

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FRACTURE BEHAVIOUR OF A DISPERSION-STRENGTHENED SAP-TYPE ALLOY *

Abstract

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References