For better observation of the microstructure of cast aluminium alloys under an optical microscope, the contrast obtained for the different micro constituents was enhanced by making use of a copper phthalocyanine based colorant. The proposed method allows distinguishing structural details which would remain hidden or poorly resolved when studying the conventionally etched sample. The method produces high relief for silicon precipitates with the tint further accentuating the outlines, allowing detection of morphology change of the aluminium- silicon eutectic due to chemical modification with strontium. Magnesium micro segregations in the α-aluminium phase, caused by incorrect thermal treatment during ageing, can also be clearly distinguished. The coloured images obtained by optical microscopy are very sharp and provide similar or better information than the corresponding Scanning Electron Microscopy images. The method proved to be suitable for Quality Control in the fabrication of cast aluminium alloy compounds, sourcing down possible errors to different stages of the process.

Item Type:	Refereed Article
Keywords:	coloured metallographic structures, optical microscopy, aluminium alloys, casting
Research Division:	Engineering
Research Group:	Materials Engineering
Research Field:	Metals and Alloy Materials
Objective Division:	Manufacturing
Objective Group:	Fabricated Metal Products
Objective Field:	Metal Castings
Author:	Dietz, C (Dr Christian Dietz)
ID Code:	96747
Year Published:	2014
Web of Science® Times Cited:	1
Deposited By:	Central Science Laboratory
Deposited On:	2014-11-19
Last Modified:	2017-11-03
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