Strongest precious metal for automoton?

I’m building a tiny automaton. The body will be white gold, but I
need to cast the mechanical parts inside (gears, struts) from the
strongest precious metal there is. Of course, I could use steel for
these parts, but I’d prefer the whole item was made of precious
metal. Is there a particular formula that would suffice for this
application that could be cast using my vaccuum caster and torch