Does it help if you think of it as an alloy of metal and air?<p>When you make steel all you are doing is forming various crystal structures, and grains. Martensite, Ferrite Austenite, Cementite, etc. They are all the &quot;same&quot; material (iron and oxygen and carbon), yet if you figure out a new way of arranging their shapes &quot;just so&quot; you can say you invented a new type of steel.<p>This is the same way - they figured out a new way of arranging the atoms, so it&#x27;s a more or less a new material.<p>(I do see your point of course, and this is more macroscopic than grains in steel, but I think it&#x27;s not unreasonable to call it a new material.)