Hello Khausik,

In response to your query in line with grain size and using Mg-Zn-Zr wrought alloy as an example. Grain refinement by Zr would manifest in increased strength of the alloy and a corresponding loss in age hardening response of the alloy. In other words, strengthening mechanism by age hardening is not favoured by grain size refinement.

Dear Jimmy,

Thanks, your answer is helpful. 

I am working with Al-Mg-Si wrought alloy. I hope the behavior should be same. 

I still want have an idea about how porosity, inter-metallic phases and morphology (globular dendrites/equiaxed) will affect age hardening behavior.

OK Khausik, I think I have a reference material by KK Alaneme (my undergraduate project supervisor) that should come in super handy. He is an expert in this field, you can direct your further queries to him via his email (check the attached article for his email). Just tell him, the recommendation comes from me.

Dear Khausik Narasimhan,

Some remarks:

* Your question assumes that grain size, casting microstructure and porosity are relevant parameters for the kinetics of age hardening precipitation as characterized by activation energy and sequence of precipitation.

* The proof of the pudding is in the eating, so your answer can be given by a comparative study based on constant alloy compositions, equal solid solution and age hardening temperatures, thereby only varying the additional kinetic parameters.

* I would not suggest to include the study of an Al alloy reinforced by ceramic particles like SiC: due to large differences in thermal expansion coefficients the presence of SiC particles may introduce misfit between particles and surrounding Al alloy, thereby introducing an additional kinetic parameter (see e.g. attached link).

https://repository.tudelft.nl/islandora/object/uuid:729cd332-fe58-4921-8262-17d150474f35/datastream/OBJ