Coupled precipitation and plasticity module:
The outstanding strength to weight ratio of age hardenable Al alloys depends upon the formation of nanoscale precipitates in Al matrix via the decomposition of super saturated solid solution (SSSS). In the traditional processing chain of Al alloys, decomposition of SSSS takes place via thermally activated diffusion process which facilitates migration and aggregation of solute atoms, which in turn results in the three well known stages of nucleation, growth and coarsening of precipitates.
However, in the ever-changing modern world, unconventional processing routes are being continuously explored. This presents us with new challenges and questions our understanding of the material behaviour. One such challenge is to understand the correlation between precipitation and plasticity. This is a complex topic in the sense that results are drastically different depending on whether plastic deformation was applied before, after or during the precipitation process. A myriad of mechanisms such as precipitate nucleation on dislocations, accelerated growth and coarsening kinetics due to dislocation mediated pipe diffusion, dissolution of precipitates and accelerated precipitation kinetics due to deformation induced vacancies have been observed whenever the two regimes have overlapped. As a result, this has posed a formidable challenge to material scientists, especially in the last decade where there has been a tremendous push to accelerate research on light alloys to cater to the global call for reducing carbon emission.
Therefore, we at the Experimental and Computational Materials Mechanics lab would like to challenge ourselves to declutter the precipitation-plasticity module by performing systematic experiments followed by extensive microstructural characterisation and numerical modelling in the Kampmann-Wagner framework. In a broad sense, the focus of this theme would be to first understand and then fine tune the interaction between precipitation and plasticity to achieve superior mechanical properties.
Projects:
- The role of monotonic and non-monotonic strain paths on the evolution of deformation induced vacancies and its role on precipitation process.
- Development of a physics-based model to predict precipitate induced anisotropy in flow stress and work hardening along different strain paths.
- Exploring the role of interrupted quenching on natural ageing behaviour and its subsequent influence on formability and paint bake response.