Reading Ternary Phase Diagrams in Materials Science (Part 5: Complex Systems, MgO-Al2O3-SiO2)

Most engineering materials are made of at least three different components. Their stability and response to changes in temperature can be mapped and understood using a Ternary Phase Diagram. These tutorials explain how to read and interpret ternary phase diagrams of interest to a Materials Scientist.
The tutorials assume some prior undergraduate-level exposure to binary phase diagrams. They explain the different methods for representing solid-state equilibria, the changes occurring upon melting and how to quantify crystallization/solidification paths for a ternary liquid.
This last video focuses how to read a “complex” ternary, MgO-Al2O3-SiO2, using the principles developed in the previous tutorials; it reviews examples of crystallization paths and reactions of different compositions and shows how the diagram can be used to fully quantify the behavior of the system.
Notes on the video content can be found here: drive.google.c...

[@user-vv3pg3ci5t]

Thank you, sir

[@Coffeebean1985]

Great video! The topic was great explained and the example really helped to understand the single steps necessary to read a TPD. Thank you very much!

[@peterdavies6179]

Thank you, glad it was helpful

[@morvaridrashtchian9395]

That was great. Thanks

[@peterdavies6179]

I'm glad you enjoyed it.

[@tataloo.hossein]

Beeeest
Best
Best 💎👑

[@peterdavies6179]

Thank you!

[@stefanomaretti3606]

Dear prof Davies thank you very much!! Really you have made a great value content in this video series. If i can i'd like ask you a suggestion. I work with traditional ceramics (tiles) where there are 7 main oxides in a tipical composition (Si-Al-Fe-Ca-Mg-K-Na). How can I approach the study of a multi element blend (for example to identify eutectic points)? In your opinion is better consider for example the ternary diagrams Si-Al-K or Si-Al-Ca and consider the sum of the minor oxides (Fe-Ca-Mg-K-Na-K) like K or Ca equivalents? Or it's better try to analyze each binary combination of different minor oxides and after ... lose the mind :)? If you can give me just a hint i'll appreciate it a lot! Thank you again

[@peterdavies6179]

Thanks for the comment: 7 component systems are tough! Of the 2 approaches you suggest, I think the first is the best first step - i.e. the ternary diagrams Si-Al-K or Si-Al-Ca and consider the sum of the minor oxides. Good luck!

[@Armandrovich]

Thank you very much for the videos, I really appreciate them. I have a question if I may, when analyzing the crystallization routes, and drawing either the tie-triangles or trapezoid, how should I know where to put the vertices for those who are solid solutions and have a range in their binary composition? Thank you!

[@peterdavies6179]

Good question: if the solid phases are pure (not solid solutions) then there is no ambiguity in their compositions and they lie on the composition of that pure solid ; however if they are solid solutions it can be difficult to be exact. Often experimental diagrams will show solid state phase compatibilities which can sometimes help in deducing co-existing compositions when there are solid solutions. Hope this helps.

[@easyvic1803]

i should go back and start from the 1st part. I really wished you picked a different composition on the pure MgO field

[@peterdavies6179]

Thanks for the comment; if you do go back to the earlier videos hopefully you can select a composition near MgO and deduce the path (the primary phase will be MgO). I think you’ll find the paths are more straightforward than the other ones in this video as the only ternary invariant reaction that could be involved is the 1710C ternary eutectic where: L -> MgO + 2MgO.SiO2 + MgO.Al2O3
Let me know if you have any questions

[@easyvic1803]

Thank you very much for the explanation. The video makes very sense. I am able to understand watching but finding a little difficult reading and working problems. Can you please help me with invariant reaction in 1453,. also finding a composition of 40 Sio2, 15% Al2O3, i know the first solid to crystallize will be fosterite, and the second solid to crystallize is spinel. But i have a question, what will be the composition at when spinel starts to crystallize. and the amount of phase presents. Also what will be the solidification pathway and where the solidification ends, with the 40%Sio2 and 15%Al2O3 .i will be glad if you can help me with this 2 problems.