Superimposed Dispersoid Hardening and Age Hardening of Aluminium Alloys

• Applicant: Professor Dr.-Ing. Olaf Keßler
• Subject Area: Metallurgical, Thermal and Thermomechanical Treatment of Materials
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 455782072

The aim of the project is the production of high-strength aluminium alloys by the novel approach of superimposed dispersoid hardening and precipitation hardening. This initially requires a basic materials science understanding of the temperature dependent kinetics and types of precipitation formation in both hardening mechanisms. Subsequently, in a typical production chain of wrought aluminium alloys (casting, homogenising, hot forming, precipitation hardening), the process parameters are to be adjusted to the two temperature-dependent kinetics in such a way that material structures with potentially high strength levels result. Based on the results, the material-scientific correlations between process parameters, material structures and mechanical properties are to be discussed and specifically transferred to the production chain for a further increase in strength. The aluminium alloy EN AW AlMn0.5Mg0.5 (3105), which is to little extent known from our own preliminary work, will be investigated with regard to understanding the superimposed precipitation behaviour and suitable process parameters of the production chain. In a further approach, an additional potential for dispersoid hardening via Al3Zr dispersoids is to be created by adding Zr.For the targeted superposition of dispersoid hardening and precipitation hardening, different approaches of potential production chains are to be pursued. The approaches are based on the fact that the diffusion coefficient of the dispersoid-forming alloying element manganese (and Zr) in aluminium at typical annealing temperatures is significantly lower than the diffusion coefficient of the precipitation-hardening alloying elements magnesium and silicon. On this basis, the aim is to form the relatively stable dispersoids in a first step of the process chain and the less stable precipitates in a second step. The second step of the process chain can be carried out at higher temperatures if the process duration is short enough to suppress significant manganese diffusion (and Zr).

• DFG Programme: Research Grants