[CarrotAndStick]

Liquid aluminum reacts very violently with oxygen, it's several times more explosive than TNT

Are you sure about that? I've handled molten aluminium to make small castings, and I'm sure it has come in contact with the oxygen in air. I do know that aluminium powder is a component of the explosive Astrolite, but that requires another exotic chemical, to be produced. This Astrolite is about twice as explosive as TNT. Perhaps you've confused the latter for the former, no?

[Kellis91789]

Ordinarily, when aluminum reacts with air, a coating of aluminum oxide (aluminum rust) forms on the outside. This is why aluminum goes from being really mirror-shiney to dull if left unprotected.

In the article, the gallium prevents the coating from forming and the pellets have a lot of surface area compared to their weight and volume. So the alumina sloughs away instead of coating the pellets, constantly exposing new aluminum to the water where it reacts to pull the oxygen away and leave the gaseous H2 behind.

[omnivore]

"Liquid aluminum reacts very violently with oxygen..."

I'd believe it. Back in shop class in school we had a small fire in the induction furnace when the teacher was melting aluminum for sand castings. Liquid aluminum burns nicely in plain air. If it was in an oxygen environment at atmospheric pressure, I wouldn't want to be anywhere near it.

I was at an industrial site once, where they had had a leak from an oxygen line. Nobody had realized there was an oxygen-rich zone downwind of the leak, because they didn't know about the leak. A guy driving through in a VW Beetle (old style) had enough sparkage in his alternator or elsewhere, or hot muffler parts, that the car caught fire going through the oxygen cloud. The guy got out in time, but the car was just a fried hulk. They left the rusted carcass of the car by the side of the road, to remind people how dangerous the oxygen could be if it leaked. In a pure oxygen atmosphere you can practically start a fire by rubbing your hands together. I realize that was steel, not aluminum, but liquid aluminum is certainly flamable. I wouldn't want to see the combination.

[dangerdoc]

Or thermite.

I think is magnesium oxide and aluminum powder.