New conductor rail pots

aluminium i think they made of as when they wear down the top surface is slid off and replaced the conductor rails that is

Aluminium traction rails have been around for a while. Long before them came the aluminium traction jumpers which I first saw at Liverpool Street Central Line in the mid 1990s. Of course aluminium is much lighter than copper and those old 935mm2 'snakes' weighed a ton and cost a fortune too with the heavy brass lugs on each end.
The trouble with aluminium as a conductor is that it oxidises quickly in air and becomes highly resistive. In the 1970s during the great copper shortage it was used by the BPO as a replacement for copper telephone distribution cables and led to crimping as the only way to make it usable as screwed connections went high resistance within a few hours of installation.

I imagine that aluminium traction rails have the advantage of a 'friction' connection as the shoes traverse them but I can't help wondering if there are any problems when a train has been stabled upon them for a few hours. It may be that 630v dc is enough to break down the oxide or is it perhaps that something is added to the mix in production to prevent such oxidisation.

Thinking about it isn't the current rail on DLR an aluminium rail? I must admit that I never looked that closely at one.

Yes the main rail is an aluminium alloy with stainless steel capping though I've always wondered how the risk of bimetallic corrosion is avoided. Perhaps the galvanic cell is disrupted by the current passed through the rail.

They look a similar design to ones I've seen on the southern region (obv taller). The SR ones aren't twisted like those though - out of interest, which way do trains run on that pic? I wonder what the twist gives?

Hmmm, can't see any specific advantage.
I wonder if there is any curvature that puts a specific lateral force on the rail there?