I'm sure it's not the blended metal technology pioneered by LeMas (which turned out to be pretty much 99.44% pure lead with a trace of antimony),
but,
going by Aquila's website it states the bullets are an alloy, meaning a combination of two or more metals, the atoms of one replacing or occupying interstitial positions between the atoms of the other: Brass is a blend of zinc and copper.
Bottom line? who knows but it sure seems to be overblown and overhyped .... and about 5 years out of being current news.