Digital Repository, ICF12, Ottawa 2009

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Short crack and near threshold fatigue behaviour of Al-Si casting alloys
A.J. Moffat, B.G. Mellor, I. Sinclair, P.A.S. Reed

Last modified: 2013-05-03


Al-Si casting alloys are widely used in automotive engines [1]. An understanding
of the interaction between damage and the microstructure in these alloys is
therefore of value in optimising the materials for improved engine efficiency. In
modern Al-Si casting alloys, large quantities of alloying additions, such as Cu, Ni
and Mg, are added to improve various material properties [2]. However, this
results in complex, multicomponent microstructures that typically contain solid
solution α-Al as the matrix phase, primary and/or eutectic Si and many
intermetallics [3]. Si and the intermetallics are considerably harder than the matrix
and exhibit a greater Young’s modulus [4]. These hard phases form an
interconnected network throughout the material [5] and so are akin to an
interpenetrating composite as opposed to a particulate system.

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