Title: The influence of Mg₁₇Al₁₂ phase volume fraction on the corrosion behaviour of AZ91 magnesium alloy

Authors: Andrzej Kielbus, Grzegorz Moskal

Addresses: Silesian University of Technology, 40-019 Katowice, Poland. ' Silesian University of Technology, 40-019 Katowice, Poland

Abstract: The microstructure and the corrosion behaviour of AZ91 magnesium alloy in the as-cast and after heat treatment conditions were investigated. The microstructure of the cast alloy consisted of an α-Mg phase matrix with a continuous and discontinuous β phase (Mg₁₇Al₁₂) at the grain boundaries. The β phase had a twofold influence on corrosion: as a barrier (high volume fraction) and as a galvanic cathode (small volume fraction). After the T4 treatment, the β phase dissolved in the matrix and after the T6 treatment, discontinuous precipitation of the β phase along the grain boundaries was observed. The microstructural examinations were conducted using light microscopy. The corrosion behaviour was investigated in a 3.5% solution of NaCl. The aim of this paper is to present the results of investigations on the microstructure of the AZ91 magnesium alloy after heat treatment.

Keywords: magnesium alloys; AZ91; microstructure; Mg17Al12 phase; corrosion; heat treatment; cast alloys.

DOI: 10.1504/IJMMP.2009.028633

International Journal of Microstructure and Materials Properties, 2009 Vol.4 No.2, pp.196 - 206

Published online: 21 Sep 2009 *

Full-text access for editors Full-text access for subscribers Purchase this article Comment on this article