I did some work with HEAs, specifically Paliney-6 and Paliney-7, and was pretty blown away by two things:

1. Material properties

2. Cost.

> Paliney® 6 is an age-hardenable palladium silver-based alloy ideally suited for demanding low current sliding electrical contact applications

I'd love to hear more, especially on #1.

And while you're at it, #2