Modified 4-Point Bending Test for Adhesion Measurement at the Interface of Iron Coated with Aluminum Casting Alloy

Abstract

In order to reduce the weight in automotive or aeronautic components, aluminum and its alloys are being used more and more. However, their mechanical properties are not as good as those of steel and can sometimes be below the necessary requirement. To overcome this issue, reinforcement of some parts is required. In this case, the mechanical reliability of the interface between the aluminum alloy matrix and its reinforcement has to be insured. This can be done by controlling the process parameters involved in developing a strong metallurgical bond between the two metals. In this work an Fe/Al–7 wt% Si alloy interface was investigated, aimed at linking the chemistry of the reaction layers with the toughness of the bond. First, the chemistry of the interface was characterized after immersion of Fe plates in an aluminum alloy melt. Then, the fracture energy of these assemblies was measured using a modified 4-point bending test for the adhesion measurement. In the case of pure elastic deformation during the loading, an analytical approach based on beam bending theory can be used to quantify the fracture energy. Nevertheless, in bonding between metallic partners, plastic dissipation can be expected. This is why a numerical calculation, based on a cohesive zone mode was proposed. The use of cohesive elements to describe the interface behavior allows for modeling both the threshold of de-cohesion and the progression of damage at each point of the interface.