Quantitative Gefügeanalyse von Aluminium-Silicium- Gußlegierungen / Quantitative Microstructural Analysis of Aluminium-Silicon Cast Alloys

Abstract

A method is described which, using the Quantimet 500, enables the semi-automatic quantitative characterisation of hypoeutectic Al-Si microstructures. Microstructural parameters are the volume fraction and mean chord length of the primary phase and eutectic phases, and the dendrite arm spacing. The difficulty in determining the microstructural parameters is that a portion of the eutectic Al phase crystallises on the primary Al dendrites. In this work the crystallisation is taken into consideration using image processing. The method used is also applicable to other alloy systems where crystallisation of a eutectic phase onto the primary phase occurs. The subjective measurement of the dendrite arm spacing is replaced by a measurement of the mean chord length of the primary dendrites and a proportionality constant is given for hypoeutectic Al-Si alloys wich relates the two parameters