Al-Cu-Sn vs. Al-Ni-Sn plating for electric contacts?

I am doing research in area of electric contacts reliability and particularly I am looking for best (and not expensive!) technology for tin plating onto aluminum bus bar.

Currently Al-Cu-Sn combination has tendency to develop intermetallic compounds and reduce contact conductivity. Al-Ni-Sn looks interesting, but I can't find reliable comparison of costs(Al-Cu-Sn/Al-Ni-Sn). Some articles say that Ni is less expensive, but I am not sure.

Can anybody help me to compare these platings? And is it a really good idea to switch from Cu to Ni?

Thanks,

Alex

There are a number of ways to plate Al bus bar. One method is stannate immersion, Bronze plate then Tin plate. Some now are plated by zinc immersion, copper plate then tin plate.

As for the cost of tin plate vs nickel plate, nickel plating is usually more expensive because the metal price is more expensive.