Abstract:Mechanical properties of Ti/Al-7Si assemblies produced by insert moulding have been studied with a classical push-out test and a variant that is the circular bending test. Special care has been taken for controlling both the reactivity at theTi/Al-7Si interface and the metallurgical health of the Al-7Si matrix. Mechanical tests until complete debonding have been completed with interrupted tests, metallographic characterizations and FEM analysis of elastic stress state. A mean shear strength of the interface of about 120 MPa has been obtained. When the Ti insert is solely fretted in the matrix, without chemical interaction between Ti and the Al-7Si alloy, the mean shear strength is significantly lower (48 MPa). This result clearly shows that chemical interaction at the interface (formation of a thin TiSi layer at the Ti side and a thick Al 3 Ti(Si) layer at the Al-7Si alloy side) improves the mechanical properties of the assembly. It is also shown that the failure sequence is characterized both by crack propagation from bottom to top and matrix yielding from top to bottom. Actually, interface damaging begins by crack initiation at the specimen bottom face (not at the top face, under the indenter) in a nearly pure mode I solicitation at a radial tensile stress of about 100 MPa.

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