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Old 10-23-2017, 08:37 PM   #1
John_A_Tallon
 
Join Date: Aug 2011
Default Amorphous metal alloy for the Cutting Edge armor rules

Amorphous metal alloys can exhibit startling material properties. The best of them that have been published is the Palladium Glass alloy developed by Marios D. Demetriou, and written about in Nature Materials (DOI:10.1038/NMAT2930). The alloy is 79% palladium, 3.5% silver, 6% phosphorus, 9.5% silicon, and 2% germanium.

As an exercise in taking a cool development in materials science and making it part of a game world, I tried putting some GURPS numbers to it. The goal was plausible fiction, with enough background information for a GM to have some fun.

Palladium Glass: An Expensive Late TL8 Material
For use with the rules on page 17 of Pyramid 3/85
Code:
TL      Material       WM      CM   DR/in.  Max DR  Min DR  Notes  Construction
8  Palladium Glass    0.13  $50,000  350     140      -       -        R/S
Comments:
Palladium glass is roughly five times as hard and tough as rolled homogeneous armor. I arrived at this by comparing the reported numbers in the literature to the standard for rolled homogeneous armor set by the military and fudging a little to make sure the material would provide an interesting alternative to other TL 8 and TL 9 materials. Strictly speaking, the alloy portrayed here is a fictional one since it slightly out-performs the one Demetriou designed.

The material is incredibly expensive but provides the best performance of the TL 8 materials, and in applications where volume matters more than weight the palladium glass composite remains a better choice than the TL 9 Polymer Nanocomposite presented in the Ultra-Tech Armor article in Pyramid 3/96. The expensive nature of the material makes it (and the technology to make it) an interesting plot hook without really risking breaking most games.

Note for Inventors and Gadgeteers:
Working with this stuff seems to be an exercise in working around the limits imposed by the conditions it requires to form. The key to any amorphous alloy material is cooling it quickly enough that it retains its non-ordered molecular structure. If it cools slowly the molecules naturally form a crystal lattice. For metal alloys this means that the best way to get an amorphous structure is to use liquid quenching on a small sample. Surface to area ratio is important, and short lengths of thin wire is the easiest shape to form and get good results. I have been unable to find literature about forming small plates of the material in fused quartz molds, but it shouldn't be impossible.

In a setting where this material has yet to be developed significantly as a technology, small plates suitable for scale mail should be considered a simple invention for the New Inventions rules in the Basic Set, as the primary obstacle would be maintaining a good quenching rate as the size of the sample increased. Making large curved and complex forms, such as for plate armor, would probably be much harder and would likely require expensive quartz molds. The construction cost multiplier in the rules accounts for this well enough for a mature technology, but when treating it as developing a new technology it is a Complex invention.

Assumptions:
I used a naive method of taking the liquid density for each of the components and multiplying that by the percentage they're present in the material and then summing the results. This gets us into "Good enough for GM work" territory, and provides a density of 9g/cm3. I used liquid instead of solid density values because the material is amorphous. This gives results that are in line with logic, since amorphous alloys are usually less dense than crystalline ones, to my understanding on the subject (caveat: I am not a metallurgist).

While the price of palladium is fairly volatile, I decided to set it at $800 per troy ounce for the purposes of figuring out the rest of the math. This is in the ballpark for the time period the alloy was developed. That means the materials costs alone, without considering energy costs or that the material must be made in a mold that can both survive the high temperatures involved and not react with the sample, are over $9200 per pound. I think it's reasonable to round up to $10,000 per pound for the material price. Using the New Invention rules, we can treat this as being 20% of retail price and thus arrive at a market rate of $50,000 per pound.
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Old 10-23-2017, 09:21 PM   #2
Anthony
 
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Default Re: Amorphous metal alloy for the Cutting Edge armor rules

Whenever you see a value like 'N times as strong as steel', the correct thing to do with it is ignore it. Amorphous metal alloys have some interesting properties that probably don't in any meaningful way correspond to being superior armor.
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Old 10-24-2017, 06:00 AM   #3
John_A_Tallon
 
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Default Re: Amorphous metal alloy for the Cutting Edge armor rules

Quote:
Originally Posted by Anthony View Post
Whenever you see a value like 'N times as strong as steel', the correct thing to do with it is ignore it. Amorphous metal alloys have some interesting properties that probably don't in any meaningful way correspond to being superior armor.
I invite you to refer to the journal article. Demetriou et al didn't phrase things in such a pat way. That was all me, based on the information they provided in their article and existing data on RHA. And as I stated, this is a fictional version of an alloy with only a limited amount of published data. I rounded up the DR numbers to make the material an interesting choice for inventor characters and GMs.
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Old 10-24-2017, 05:02 PM   #4
sir_pudding
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Default Re: Amorphous metal alloy for the Cutting Edge armor rules

Is there an real world interest in developing body armor based on this? Even hypothetical? That would be a key indicator to me that this is plausible or not.
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Old 10-24-2017, 05:10 PM   #5
Anaraxes
 
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Default Re: Amorphous metal alloy for the Cutting Edge armor rules

Quote:
Originally Posted by John_A_Tallon View Post
The alloy is 79% palladium
If I'm reading my quick search correctly, total world palladium production is around 200 tons. What are you going to do for the second tank platoon in your army?
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Old 10-24-2017, 06:59 PM   #6
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Default Re: Amorphous metal alloy for the Cutting Edge armor rules

If you are interested in new materials for cutting edge armor, metallic foam composites look interesting. Vehicle armor is mentioned in the first paragraph as a potential application.
https://news.ncsu.edu/2016/04/metal-foam-tough-2016/
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Old 10-24-2017, 08:35 PM   #7
onetrikpony
 
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Default Re: Amorphous metal alloy for the Cutting Edge armor rules

This is cool. Works well for gadgetiering.
and that's a useful reference.

Thank OP. :)
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Old 10-24-2017, 11:35 PM   #8
John_A_Tallon
 
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Default Re: Amorphous metal alloy for the Cutting Edge armor rules

Quote:
Originally Posted by sir_pudding View Post
Is there an real world interest in developing body armor based on this? Even hypothetical? That would be a key indicator to me that this is plausible or not.
No, because palladium is prohibitively rare and expensive. The research on palladium glass focused on characterizing the strength and hardness of the material in the cheapest way possible (it was actually pretty clever). The real immediate value of the research seems to be that it demonstrated that Demetriou's method for designing an amorphous glass alloy with certain desirable properties was sound. He didn't make the alloy through experimental iteration but through targeted design using what he knew about amorphous alloys.


Quote:
Originally Posted by Anaraxes View Post
If I'm reading my quick search correctly, total world palladium production is around 200 tons. What are you going to do for the second tank platoon in your army?
That would depend on the setting. In an asteroid-belt hopping game I would expect palladium to be an order of magnitude more common. Likewise, some settings with magic would probably be able to transmute or magic up the metal needed. And in a palladium poor setting like modern day Earth, it still could be useful for heroes and villains.


Quote:
Originally Posted by Shostak View Post
If you are interested in new materials for cutting edge armor, metallic foam composites look interesting. Vehicle armor is mentioned in the first paragraph as a potential application.
https://news.ncsu.edu/2016/04/metal-foam-tough-2016/
Interesting link. I might take a crack at turning that into GURPS stats someday soon. Thanks.

Last edited by John_A_Tallon; 10-24-2017 at 11:39 PM.
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Old 10-25-2017, 03:55 PM   #9
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Default Re: Amorphous metal alloy for the Cutting Edge armor rules

I do not know how realistic such material is as armor material and what level of protection it would give. But I would definitely classify any better material that is not even in prototype product phase today as TL 9 not 8.

We are on threshold of some TL 9 technologies, with some clearly TL 9 things already in prototype/early trial stage, so anything that is not even at that stage is most likely TL 9.
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Old 10-25-2017, 06:46 PM   #10
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Default Re: Amorphous metal alloy for the Cutting Edge armor rules

Quote:
Originally Posted by John_A_Tallon View Post
I invite you to refer to the journal article. Demetriou et al didn't phrase things in such a pat way. That was all me, based on the information they provided in their article and existing data on RHA. And as I stated, this is a fictional version of an alloy with only a limited amount of published data. I rounded up the DR numbers to make the material an interesting choice for inventor characters and GMs.
The real reason you should mostly ignore such numbers is perhaps a bit subtle.

Hardness or rupture energy or whatever values for exotic new materials are almost always either calculated, or reported for very small samples. Values in the literature for steel are almost always measured for bulk samples. Why does that matter? Because the real world numbers for actual materials account for stuff like imperfections, cracks and scratches. If you use the same kinds of calculated or too small a diameter to be cracked numbers as is typical for new materials, you can easily conclude steel is 5 or 10 times stronger than steel.
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