How did it start

 THE BEGINNING OF MISCIBILITY GAP ALLOYS

Our team were working on the direct conversion of concentrated solar energy into electricity using thermionic emission. Thermionic devices (schematic shown in the image below - taken from PhD thesis, A. Post) operate at very high temperatures and being solar powered, our device would require storage to operate at night.

A quick review of thermal energy storage research highlighted that low thermal conductivity and the need to pump the molten storage material around were the major drawbacks of the existing salt based systems. In a single brainstorm session, we worked out that a very promising solution was to use alloys that have a miscibility gap. We also worked out that just casting them into shape from the molten state wouldn't work as the lower melting point metal would form the matrix phase and on heating, the whole storage alloy would slump at the active phase melting temperature. To avoid this we concluded that powder metallurgy methods would be best suited to the manufacturing MGA storage blocks.

Next we researched all of the possible binary (two-metal) systems that didn't have economic (e.g. gold) or health (e.g. uranium) problems and manufactured some prototypes from Al-Sn and Fe-Cu. When these worked out first time, we knew we were on to something good. The idea was adopted for patenting by the University of Newcastle and some seed funding provided.

Since then, we have been concentrating on a wide range of things:

1. Discovering new systems for Concentrated Solar Power (CSP) seemed to be the greatest immediate problem requiring a good new thermal storage system. Therefore, we focused in the lab on systems matched to the production of steam in the temperature range 400° - 700° C that had the lowest material cost. Systems like graphite-Zn, iron-magnesium and graphite-magnesium among others.
2. As our initial samples were only 15mm in diameter, scaling up was an important challenge. We can now make storage modules up to 1 litre in volume and these can be stacked into larger storage blocks. 
3. Further scale up to bigger storage modules. 
4. Thermal modelling of heat flows in a two-phase mixture where one phase melts. 
5. Other new alloy systems including high temperature systems with energy density 1-2 MJ/L. 
6. Flux modelling to see at what rate radiant heat could be absorbed by an MGA block. 
7. Neutron diffraction to observe the distribution of molten particles in situ during charging or discharging of an operating MGA