The development of an electrolytic etching process for examining the microstructure of thixocast magnesium alloy AZ91 hp

Magnesium is a material of the future because of the potential it's low den sity offers in the field of lightweight construction. An important factor in the development of magnesium alloys, in addition to developing new and innovative ways to fabricate them (e.g. Thixocasting), i s the ability to characterise their microstructures. Whilst microstructural analysis may seem a relatively complicated way of analysing the processing capability of such alloys, it nevertheless remains one of the most importa nt methods of metallurgical investigation. This article concerns the development of a quick and reproducible method of metallographical microstructural examination for the high purity magnesium alloy AZ91 hp by electrolytic etching (anodic oxidation). This method of e tching produces a clear colour differentiation between the individual grain s of the alloy's microstructure and thus a way of almost automatically dete rmining of all it's relevant microstructural characteristics.