Three-dimensional study of Ni aluminides in an AlSi12 alloy by means of light optical and synchrotron microtomography

• Published in: Acta materialia 2009-08, Vol.57 (14), p.4125-4132
• Main Authors: Asghar, Z., Requena, G., Degischer, H.P., Cloetens, P.
• Format: Article
• Language: English
• Subjects: 3D light optical tomography; 3D X-ray microscopy; Aluminium alloys; Applied sciences; Exact sciences and technology; Metals. Metallurgy; Ni aluminides; Synchrotron radiation
• ISSN: 1359-6454; 1873-2453
• DOI: 10.1016/j.actamat.2009.05.010

The three-dimensional (3D) microstructure of an AlSi12Ni alloy in as-cast and in solution-treated conditions is characterized by light optical and synchrotron tomography. Eutectic Al–Si alloys containing 1 wt.% Ni in as-cast condition present networks of connected Si lamellae as well as complex 3D shapes of Ni-containing aluminides. The eutectic Si networks disintegrate during solution treatment in the binary Al–Si alloy while they remain connected in the Al–Si–Ni alloy. The contiguity between eutectic Si and Ni-containing aluminides is maintained, when the alloy is solution treated at 540 °C for 24 h. The sphericity of the aluminides is only slightly increased by the solution treatment. The reinforcing role of eutectic Si together with the Ni-containing aluminides is governed by a stable interconnectivity and contiguity of these rigid phases accumulating ∼20 vol.%. The 3D data obtained by synchrotron tomography quantify connectivity, shape and volume fraction of eutectic Si and aluminides, whereas their contiguity is verified by light optical sectioning tomography.