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Isn't that the same material used in the base of classic Hot Wheels cars? I had some drive rails stump me a while back until I snapped them. Zinc has that distinct porous look when broken. I think my Dad used to call it "pot metal"

Potmetal is a very specific class of alloys. Very soft low melting point metals.
Tin and lead is most common (pewter) but with addition of chrome (skunk), aluminium (Alsoft), copper (various bronzes), or silver (silveride).

The term comes from automotive metal casting. Low melt scraps were literally melted together in a clay or iron ‘pot’ cauldron. A great early method of industrial recycling.

With that pointed out, hot wheels are not and have never been potmetal: which is why they are so highly valued by collectors over other micro replicas. For most of their life they were clean die cast aluminium. Though in the mid 80s for an undetermined length of time the body was made of an aluminium and nickel alloy.
Based on terracycle (If I recall correctly) info on a prior collection program Today they’re made from recycled automotive aluminium. Body panels and rims. Making it “irony aluminium”. Hence them being ever so slightly magnetic.

Matchbox on the other hand has always used soft-ish alloys. Lead and aluminium prior to the mid 70s. Tin and aluminium after. With most of the bod stamped steel and later plastic as well.