Korean Institute of Surface Engineering

pISSN : 1225-8024 | eISSN : 3399-8403


공학

한국표면공학회지 (17권2호 29-40)

ALLOY STRUCTURE AND ANODIC FILM GROWTH ON RAPIDLY SOLIDIFIED AL-SI-BASED ALLOYS

ALLOY STRUCTURE AND ANODIC FILM GROWTH ON RAPIDLY SOLIDIFIED AL-SI-BASED ALLOYS

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Kim, H.S.;Thompson, G.E.;Wood, G.C.;Wright, I.G.;Maringer, R.E.;

University of Ulsan;Corrosion and Protection Centre, UMIST;Battelle Laboratories, Columbus;
University of Ulsan;Corrosion and Protection Centre, UMIST;Battelle Laboratories, Columbus;

Abstract

The structure of rapidly solidified Al-Si-based alloys and its relationship to subsequent anodic film growth in near neutral and acid solutions have been investigated. Solidification of the alloys proceeds via pre-dendritic nuclei, associated with rugosity of the casting surface, from which cellular-type growth, comprised of aluminium-rich material surrounded by silicon-containing material, emanates. Observation of ultramicrotomed sections of the alloys and their anodic films reveals the local oxidation of the silicon-rich phase and its incorporation into the anodic alumina film, formed in near neutral solutions. Such incorporation occurs but resultant isolation of the silicon-rich phase is not possible for anodizing in phosphoric acid, and a three-dimensional network of the oxidized silicon-containing phase, with continuing development of porous anodic alumina, is observed.

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