Correlative Tomography – Combining x-ray nanotomography and FIB/SEM serial sectioning to analyze Al-Si cast alloys

Abstract

Aluminium alloys with silicon as their major alloying element are widely used in die or sand casting of machine or vehicle parts. The microstructure of hypereutectic Al-Si alloys (>12% Si) consist of primary silicon particles and the Al-Si eutectic. Elements such as Cu, Mg and Ni are added in order to form a great variety of different intermetallic phases which improve mechanical properties at elevated temperatures. Size, shape and connectivity of these complexly formed intermetallic phases play a decisive role for the properties and are for that reason of great interest. As the complex shapes and connectivity are not accessible by means of classical 2D techniques, 3D analysis of the microstructure is mandatory. Due to the size of the particles in the ?mrange, only high resolution 3D imaging techniques are suitable. In this work we used 3D X-ray Microscopy as well as FIB/SEM Serial Sectioning to image the microstructure of an AlSi12Cu4Ni2Mg cast alloy. 3D images were taken at the very same sample volume in order to compare information gained from the different techniques.