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I am making a paper about metals and would like some help with this issue.

If you have some kind of explosion, is it then possible for aluminium alloys to become powder particles?, if yes, can they become pure elemental aluminium particles?, or will they always be aluminium oxide particles because of that they are exposed to air?.

A metal powder expert that has given me some advice said "I have never considered metals becoming powder by an explosion – in an explosion, they would usually melt and become droplets, especially aluminium and magnesium that melt quite easily. Both aluminium and magnesium are quite soft metals, so they would bend instead of breaking easily. I cannot really see how aluminium or magnesium would turn to powder in practice." Is there anything that you guys know of that makes magnesium any different and prevents it from becoming a powder in its alloy form when an explosion occurs?.

And if your only source of aluminium alloys is from wall panels and window frames, and we say that some of this aluminium becomes powder in a explosion in a hot fire, aluminium oxide can never make a exothermic reaction together with iron oxide powder as i understand it, the aluminium would need to be in the pure elemental form for this to happen. Then in this scenario with the explosion in a fire and the unlikely scenario of aluminum alloys becoming powders, there would also be the problem that you would need a rather large quantity of such fine powders, well mixed and packed tightly together, so the reaction can be sustained.

As they say in this link about the theory of naturally occurring thermite reactions "A solid aluminum construction, or a tool made out of it, won't do. Even less likely as aluminum also slowly forms a thin oxidized layer naturally" https://space.stackexchange.com/questions/9058/could-aluminum-undergo-a-thermite-reaction-with-martian-dust

I was told this by someone regarding explosions and aluminium, what do you think about it?,

"It depends on how much pressure the aluminum alloy is exposed to. Explosion pressure can range from 1MPa to 52.82GPa for the most powerful experimental explosives.

Aluminum alloys are usually ductile and can undergo significant plastic deformations before they rupture, therefore extremely high pressures will be required to turn them into powder. This is possible if aluminum alloys are very close to source of strong explosion. If far away it’s unlikely to happen even if explosion is strong. Best way to achieve pulverization is to confine explosive itself in aluminum casing. Powerful military explosives like PETN, RDX, HMX,TNAZ, MEDINA (or experimental ones like DDF, HNC, ONC) have sufficient power to turn strongest metal alloy known to mankind into fine powder in this way.

This is evidenced with high speed camera footage's like the one: https://youtu.be/qmIjD16pK0Y

As far of purity of such powder, it will definitely oxidize in air in high extent considering that there is sufficient thermal and pressure impulse to start reaction with oxygen. Actually this is the basic principle of thermobaric weapons. Typical design is to surround small conventional explosive called “scatter charge” with fine metal powder (aluminium, magnesium). Event if explosion is done in pure nitrogen atmosphere, part of aluminum would be turned in aluminum nitride AlN.

As far of explosions in vacuum if aluminum powder is created as mentioned before, it would still react in high degree with gasses created from explosion. This principle is used to enhance explosive power in some explosive mixtures where aluminum powder is mixed with explosive itself. Aluminum reacts with gasses and releases more energy than pure explosive. Examples are explosives like Torpex, Astrolite A, Amatol etc."

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In the case of an aluminum housing with a high explosive inside, there is no time during the explosion for the heat released to be conducted all the way through the housing walls, softening them. For this reason, in the initial phases of the explosion- in which the housing disintegrates- the aluminum is still solid and will be shattered into tiny pieces.

What happens next depends on the chemical environment created by the product gases of the explosion. If they are oxidizing, then the aluminum shards will burn into oxide dust with particles the size of smoke.

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  • $\begingroup$ So even if the explosion happens next to the housing walls you mean that there is no time for the heat to soften the aluminium that you mean is a must for the aluminium alloy to be reduced to smaller particles?, it is not only about that you need extremely high pressures then?, you also need some heat?. With particles the size of smoke do you mean down to this size of one nanometer? "Smoke particles (and by smoke I mean combustion products) come in sizes all the way down to 1nm (0.001micron)" publiclab.org/questions/warren/08-30-2017/… $\endgroup$ – Andy Ljunggren Feb 24 at 19:37

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