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Sturgeon's House

New Lightweight Iron-Aluminum Alloy Is Stronger Than Titanium


Sturgeon

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*Babby dreams of his new 1 kilogram AR-15*

 

Though, damn, the west really is slowly losing out to East Asian countries in the field of materials discovery and research it seems.

 

....Which reminds me, there was something I was going to post about related to this.

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If this pans out, it could be an excellent barrel material. Currently, the limiting factor on barrel weight is not actually the strength of the barrels, but their heat capacity. A lower density steel alloy would probably have a higher heat capacity, for a lower weight, substantially reducing the mass of the most major component.

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If this pans out, it could be an excellent barrel material. Currently, the limiting factor on barrel weight is not actually the strength of the barrels, but their heat capacity. A lower density steel alloy would probably have a higher heat capacity, for a lower weight, substantially reducing the mass of the most major component.

I'm going to say no, sadly. Your hardness would be absolute shit (with the possible dodge of maybe being able to hard anodise the piece), so it wouldn't work for a barrel.

 

It is, however, good news for aerospace and armour researchers.

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What I remember from high school chemistry is that metals have very similar gravimetric thermal capacity to each other.  Something about how metallic bonding is.  So a new metal is unlikely to have vastly better heat capacity.

 

Intermetallics are interesting though.

 

Aluminum has got like double the heat capacity of steel, tho.

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Huh, so it does.  And Beryllium has about double Aluminum's specific heat capacity.

 

Maybe my textbook meant similar heat capacities relative to covalently bonded substances.  Water has about five times the specific heat capacity of aluminum.

 

Beryllium itself is also really interesting, It's well known for also forming retardedly strong alloys in certain cases.

 

(Example being that Beryllium-Copper is insanely strong and durable compared to literally any other copper based alloy.)

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For gun barrels you'd want high shock resistance, very good tensile strength, excellent hardness, low galling tendency, and excellent retention of those characteristics as the alloy heats up.  Not all alloys lose strength uniformly as the temperature rises:

 

718plus-Fig3.jpg

 

A comparison of nickel alloy tensile yield strength vs. temperature.

 

So you'd want to know the temperature range where the material characteristics remain acceptable, and then multiply that by specific heat capacity over that temperature range.  That, times your barrel mass, would be (something like) how much heat the barrel could take, ignoring the fact that the heat distribution would depend on the conductivity of the barrel material.

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Why would the hardness be shit?

As before - good ductility is generally not well correlated with good hardness.

Beryllium itself is also really interesting, It's well known for also forming retardedly strong alloys in certain cases.

(Example being that Beryllium-Copper is insanely strong and durable compared to literally any other copper based alloy.)

I love me some beryllium bronze.

For gun barrels you'd want high shock resistance, very good tensile strength, excellent hardness, low galling tendency, and excellent retention of those characteristics as the alloy heats up. Not all alloys lose strength uniformly as the temperature rises:

718plus-Fig3.jpg

A comparison of nickel alloy tensile yield strength vs. temperature.

So you'd want to know the temperature range where the material characteristics remain acceptable, and then multiply that by specific heat capacity over that temperature range. That, times your barrel mass, would be (something like) how much heat the barrel could take, ignoring the fact that the heat distribution would depend on the conductivity of the barrel material.

Adding: this new alloy is reliant on some pretty fancy heat treating to work. My suspicion is that if it gets too hot it turns into something like duralumin.

Edit: nope. The magic is in the nickel nucleation of B2 formation. The heat treatment is at a high enough temperature so that it will only become an issue when the barrel begins to glow. At which point the barrel would be ruined, but that's not exactly surprising.

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Thanks for the feedback. As you can tell, I am not a metallurgist. I have changed the article to suggest it as a barrel jacket material, perhaps in use with a 4150 liner. You can also use aluminum for this, of course, but at least I don't have to baleete a whole paragraph in my article this way.

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I wonder what happened to those thin-walled, carbon fibre-wrapped barrels that briefly made it into the sci/tech news feeds a few years back?

They all caused the M4A2s they were attached to to malfunction by causing the striker to shoot sideways out of the belt feed mechanism, shattering the shoulder thing that goes up and flying out with enough force to fatally impale one of our brave peacekeepers stationed all the way in South Africa.

 

THESE ARE OUR STANDARD ISSUE RIFLES, WAKE UP SHEEPLE!

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Rather than start a new thread, I'll put this article here about Boeing developing a light-weight metal lattice that is "99.99 percent air".

 

http://www.dailymail.co.uk/sciencetech/article-3270060/The-end-heavy-metal-Boeing-shows-material-99-99-AIR-lead-new-generation-planes-spaceships.html

 

https://www.youtube.com/watch?v=1EC8HtGwUeM

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I'd wonder about a FeAl alloy's corrosion resistance.  Aluminum+steel+humid environment often equals loads of corrosion.

 

Yes but Aluminum + Oxygen + the right environment = precious gemstones!

 

Do you have aluminum in your shop Meplat? let's make lots of money!

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I'd wonder about a FeAl alloy's corrosion resistance. Aluminum+steel+humid environment often equals loads of corrosion.

My understanding is that the iron forms insoluble grains in the aluminium (edit: nope, I was thinking of Fe in Al, Al in Fe produces that B2 form the research team were controlling formation of). So any corrosion is likely to be of the really nasty kind where the material delaminates and puffs up from the edges.

Sturgeon, if you're keen on posting material science-related stuff on TFB then a good way to find content might be to sign up for email alerts on a few interesting journals (the Journal of Impact Engineering is a favourite of mine) and then give me a shout if you find an abstract you want the full version of. I still have access to a university journal portal, so I can get hold of paywalled stuff a lot of the time.

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Sturgeon, if you're keen on posting material science-related stuff on TFB then a good way to find content might be to sign up for email alerts on a few interesting journals (the Journal of Impact Engineering is a favourite of mine) and then give me a shout if you find an abstract you want the full version of. I still have access to a university journal portal, so I can get hold of paywalled stuff a lot of the time.

 

Ooh, how do I sign up for those?

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Yes but Aluminum + Oxygen + the right environment = precious gemstones!

 

Do you have aluminum in your shop Meplat? let's make lots of money!

Scads, sadly it's attached to vehicles I am paid to work on and/or keep reasonably intact.

 

My understanding is that the iron forms insoluble grains in the aluminium (edit: nope, I was thinking of Fe in Al, Al in Fe produces that B2 form the research team were controlling formation of). So any corrosion is likely to be of the really nasty kind where the material delaminates and puffs up from the edges.

 

"Intergranular" I believe is the term you wanted.

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