The tagline of ausheds is actually an uncivil insult of Jack...

The tagline of ausheds is actually an uncivil insult of Jack Lifton, who believes in the criticality of ex-China sourcing of all magnet metals including Dy and Tb. ausheds OTOH does not think Dysprosium is worth investing in; he believes any such investment to be as stupid as investing in a waning market like horseshoes in 1920. LOL, he is a glib one. So he told good old Jack to go jump, then declared he had won the argument forever and ever, then penned his signature as a permanent gloat he describes as "having a piss on Jack".

But I digress.

The big thought on Tb is that it does the same job as Dy in the largest market for both: permanent magnets aka DyTb:NdPrFeB. The choice for EVs and many wind turbines esp offshore.

Both elements have other uses related to their unique optical properties, but both are seeing increased use as thermal stabilizers of NdPrFeB magnetic strength. The amount of DyTb needed depends on the temperature and other magnetic fields that the magnet will be operating in. The higher the temperature, the more DyTb is needed. At EV motor temps, current motors contain magnets with ~3% DyTb. The EV motor business will drive value of DyTb.

The DyTb replaces the NdPr in a magnet. So while "pure" NdPrFeB is about 30-31% NdPr, a magnet containing 3% DyTb can only contain 27-28% NdPr. That weakens that magnet proportionally. If one separates DyTb and uses pure Tb, whose effect is stronger than Dy (and there is a reported role for Ho as well), then the magnet strength can be dialed back up a little (using less Tb to protect from same amount of heat allows more NdPr to remain).

Apparently (I have read) this expensive practice is common in wind turbine magnets because of the very high value of every rotation of the blades. Thus, in my opinion, the value of terbium will be driven largely by the wind industry's outsized use of it, both onshore and off and of all topologies.