Increasing thermal conductivity of Al/Cu hybrid components using powder pressing and subsequent semi-solid forming

• Applicant: Professor Dr.-Ing. Mathias Liewald
• Subject Area: Primary Shaping and Reshaping Technology, Additive Manufacturing
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 544870268

As part of the automotive electrification and the increasing demand for renewable energies, power electronics is becoming a key technology for future mobility and energy supply. Due to the high thermal load of such power electronics components, however, cooling them represents a major challenge. Here, hybrid material structures do offer the possibility of combining different mechanical and thermal material properties and thus meeting diverse functional requirements in one single component. When producing such hybrid components, particular attention must be paid to the transition zones between both metallic compound partners. For this reason, a novel process route for the production of interface-optimised aluminium-copper compounds has to be developed and investigated within the scope of the research project proposed here. The novel process route is based on the infiltration of graduated, porous copper green bodies by means of a semi-solid aluminium alloy. Aim of this infiltration is to increase the contact area between the compound partners and to avoid entrapment of air as well as the development of intermetallic phases. Thus, a form and material locking is achieved in the interface between copper and aluminium, which leads to improved thermal properties, in particular the heat transfer. In order to understand the thermophysical interactions of the process route, at first a numerical model must be developed. Subsequently, both processes will be numerically designed in order to determine the process limits as well as the ideal process parameters. Afterwards, copper green bodies with different height/diameter ratios and different density distributions are produced and subsequently infiltrated with the semi-solid aluminium alloy AlSi7Mg0,3. The infiltration quality is characterised by means of infiltration depth, interface reactions and the thermal conductivity occurring in the material transition. The experimental results will be used to validate the simulation results. Based on the measured thermal conductivity in the interface a comparison of the compounds to conventional joints will be made. In summary, the goal of the research project is to significantly increase the thermal conductivity in the interface of hybrid components made of aluminium and copper and to enable a numerical process design for the production of corresponding hybrid components.

• DFG Programme: Research Grants