It sure does! Have you ever seen a piece of zone-refined Silicon from the electronics industry? It looks and behaves like glass.

You're probably remembering the fact that pure metals are typically very soft. If you look on the periodic table, Silicon is a nonmetal. The only way you could get SiO2 in the casting is from burned-on sand or entrained inclusions from the melt, either of which is highly undesireable.

By the way, I've actually poured metal to produce Al-Si alloy castings in our lab for prototype parts and I've studied these alloys using various microscopy techniques. I am quite intimately acquainted with these alloys and their problems.

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