Indestructible Material

[NOLAN]

Hi guys,

 

I'm looking for extreme materials, and now I'm looking for virtually indestructible materials, such as stuff that can withstand being hit with a train travelling at Mach 3.

[Phi for All]

Hi guys,

 

I'm looking for extreme materials, and now I'm looking for virtually indestructible materials, such as stuff that can withstand being hit with a train travelling at Mach 3.

First we have to invent a train that can travel at Mach 3.

 

When you say "withstand", what exactly are you talking about? If you had a train that could travel at Mach 3, an ordinary piece of paper could withstand impact with the front of it and come out whole if a bit crumpled. Are you talking about a material that could be stretched across the tracks and would remain there as the train accordioned against it car by car until there was just a block of mashed steel up against the barrier?

 

Does this material have to be impervious to anything? There are materials that could more easily withstand impact than they could being dipped in acid.

[Enthalpy]

Materials that survive to shocks? It was part of a former job, and past 30m/s it became difficult. I'd say 100m/s is a limit under extremely (=impractical) conditions on the shape of the object.

 

Just brittle alloys, as hard as possible, are a good choice to survive a shock repetitively - say, tooling steel. The parts must be designed so the shock wave stays below the yield strength, not trivial at all. Soft materials are better against a single shock, but as they deform at each shock, they get unusable.

 

An other possibility is a damping material, that dissipates the mechanical energy but regains its shape... more or less, and after some time. This materials are difficult to use because they creep, but just polyurethane is an excellent candidate (the best one). Though, at 120km/s and not Mach 3, I've seen many PU parts fail. Also, they're hard to predict by computation.

[h4tt3n]

Nolan, try google "metallic glass" or "amorphous metal". That's probably the closest we get to UFO-metal or adamantium or whatever you want to call this stuff. In short, metallic glasses can be just about any metal or combination of metals and non-metals that have been cooled down so fast that it didn't have time to crystallize. The "glass" part simply means that it is amorphous, ie. without crystal structure (it doesn't mean you can see through it). Metals without crystal structure are *extremely* tough, but tecnically speaking they are not necessarily hard. This means you can deform them a lot without building up tension and breaking it. When "regular" metals deform, the tiny metal crystals slip on each others surfaces, or the usually well aligned atoms inside the crystals shift along different planes. More possiple slip planes means you can deform it more easily without braking it. Now, amorphous metal does not have any structure at all. The atoms are placed in a non-repeating random pattern. That's why metallic glasses are very very difficult to deform compared to "regular" metal. The problem is, these metallic glasses are very hard to make in large quantities, because you can't cool it fast enough. Metallic glass made in labs is usually very thin sheets of alloy sprayed or shot onto very cold surfaces.

 

A few links to articles:

 

http://link.springer.com/search?query=metallic+glass&showAll=false

 

http://link.springer.com/search?query=amorphous+metal&showAll=false

 

Hope this helps!

 

Cheers,

Mike

[Enthalpy]

Is a permanent deformation acceptable?

 

If not, only hardness help. Some amorphous metals, including magnetic materials, have 3500MPa yield strength and virtually no elongation at break, just like some tool steels, but this limits the elastic asymmetric impact speed to 80m/s, far from Mach 3.

[NOLAN]

I mean the ability to maintain its original shape.

Enthalpy, that was more or less what I meant.

[Mr Monkeybat]

Is this for a science fiction story? As super strong materials Graphene and carbon nanotubes are the height of speculative fashion. Harder than diamond with a fracture strength 200 times greater than steel this stuff is tough.