Alternative alloys for weapons and armor?

Question

What other hypothetical alloys could be used for ancient/medieval era weapons/armor?

• Don't use made-up elements (or alloys, if possible)

• Assume metallurgical technology up to the medieval age (in any of Earth's societies, such as Europe, China, Japan etc.)

• Assume normally rare elements to us could be in abundance (perhaps those from meteorites or other similar objects)

• Consider various types of strain, density and various types of stress to determine good candidates

EDIT

I've changed the question to put more emphasis on the alternative alloys part rather than the rare elements part. Is it really the case that given different circumstances, the same weapon alloys would be made? For example: steel and bronze.

Answer 1

Ultimate tensile strength

Let's start by making the usefulness of an alloy measurable. I'll use the unit MPa as a proxy for of puncture strength.

For the sake of comparison, here are some values:

• human skin: 20
• aluminium: 45
• gold: 100
• copper: 210
• iron: 350
• brass: 550

Judging by this table brass appears to be the best choice for armor and indeed it is. At least as long as you don't want to move so much. Brass has a higher density than iron (8.7 to 7.8). Also you need to keep in mind that brass is more expensive than iron.

Precipitation hardening

Now, in order to get some decent alloys your civilization needs to know the art of precipitation hardening which ain't that hard if you use materials which have a low melting point like aluminium.

Magnesium Alloy

If your civilization discovers magnesium (high probability as it is earths fourth most abundant resource) you have another high potential component for creating strong alloys.

If you'd put aluminium and magnesium together you can create a very strong alloy with a MPa of 450 (Aluminum alloys) and very low density, making it lightweight armor more powerful then iron. Using a lightweight material like this would allow you to construct plate-armors in which you could move around more freely or a chainmail nearly as light as a leather armor but much more pierce resistant. Using it as a weapon on the other hand has the weight disadvantage as you need some weight to cut through armor or break some bones. You should therefore not use it for a non-cutting weapon.

There are much more aluminium - alloys and magnesium alloys. Take a look yourself, but most of these alloys demand a higher level of technology. Take a look at the aluminium-zinc alloy with an MPa of 700 for example.

Cermaic Armour Plates

You could use ceramic plates in vests to get a high penetration-protective armor. Ceramic is used in a lot of modern composite armors and bullet proof vests. Ceramic armor is however a one-use armor as the ceramic tends to shatter after receiving a blow or two. As ceramic is much lighter than steel or iron, ceramic vest seems to be useful to skirmishers - fast attack, fast withdraw, minimal casualties.

Silk Armour

This sounds ridiculous at first, but the Mongol horde used silk armors which were much more penetration-protective than European plate armor. Above the thick silk armour they've worn a scale armour to protect them from cutting damage. The silk armour was super effective as it was very light an hardly penetratable by spears and arrows alike. Silkworm silk has a density of about 1.3 and an MPa rating of 500. It's obviously not suitable as a weapon.

Answer 2

The development of bronze (and it was the king of metal weapons and armor for about 5 millennia) is due to a number of factors. First, it is (obviously) derived from copper. And copper has a number of peculiar advantages. First, copper ore deposits are often associated with small amounts of native copper. Copper has two relevant virtues: it has a low melting point and it can be work-hardened. So those lumps of native copper can be made into weapons that are superior to bone and stone without an enormous tech base. And the copper ores found nearby can be purified by just heating (rather than requiring a non-obvious flux), so the same techniques used to work native copper might lead to the discovery of smelting without too much effort. Once the general idea is discovered, it's not unreasonable to hope that some metal worker of an experimental frame of mind will take the idea further. It didn't take much to notice that adding other metals produced a metal which was much easier to cast, and was stronger and harder than pure copper. (ETA - Although those additional metals were added as other ores or minerals, rather than as finished ingots.)

The first bronzes were arsenic bronzes, but at some point it was noted that tin gave superior results. This was not immediately useful, as arsenic was often associated with the ore complexes that produced copper, but by Roman times the exploitation and trade of British tin mines was well-established.

Alloying copper and zinc produces brass, which is actually harder than bronze, but the major zinc deposits are in North America, Australia, and Iran. The first two don't count, but it's not clear why no trade was established to provide Iranian zinc to replace British tin.

There are several other possible bronze alloys, especially aluminum and silicon. Both of these require much higher temperatures than tin.

So, for development of copper alloys, arsenic bronze, tin bronze and brass are about the only contenders, and it's just not clear that there's much to choose between them as far as weapons and armor go.

Are there any alternatives? Looking at what produces native metals (to get the development process going), not much. Gold and silver (while tempting from an aesthetic point of view) can be melted at low temperature, but they just don't produce materials that are either strong or hard. Some of the platinum group metals (like platinum, for instance) can produce a fairly hard metal, but they all have high melting points. Other metals which have reasonable melting points tend to be soft, and the harder metals tend to have a high melting point. Before the development of coke, even iron was very difficult to melt, and was usually produced as blooms which were purified by working (hence "wrought" iron). Plus, of course, many are difficult to produce as they oxidize rapidly at high temperature.

So, all things considered, the only semi-major change I can suggest is the replacement of bronze with brass, and that means your fictional society hasn't made it into the Iron Age.

Answer 3

I'll add on answer despite one being already chosen since I want to add some things that I did not notice being mentioned and it doesn't make sense adding a "list of stuff nobody mentioned that I could see" as a comment to either a random answer or the question.

Copper alloys

Already mentioned by others, but I noticed nobody mentioned why people transferred to using iron as soon as they had the technology.

Simply put copper alloys are too ductile. If used as weapon they have a tendency to deform, bend, and lose any sharpness the brownsmith tried to give them. This makes them pretty much useless for any weapon with a point or edge. And weapons with a length of metal such as swords and some polearms would have issues with bending.

On a positive note they are hard to break, which is why they were used for cannons and cartridges. Similarly they would probably (if cheaper due to the metals being more common) see use in armor. Bronze and brass actually were used in armor despite iron being available, if it was affordable.

Meteoric iron

First thing that occurred to me with some metals being more common than on Earth for some reason. If the area of your civilization was hit by a rain of iron-nickel meteorites, meteoric iron could be common enough to cause a fundamental change in metallurgy.

Why does it matter what kind of iron you use? Because meteoric iron is actually a nickel-iron alloy. It is found as pure alloy, no refining is needed. The nickel content also gives it much better corrosion resistance. Most alloys are also easier to work than iron, I think.

As a bonus it can have an exotic crystalline structure that looks pretty, might be magnetic (aka "magic") and can legitimately be said to be a gift from heavens.

A side-effect is that such abundance would probably be localized, so a specific area would probably have big edge on availability.

Also note that nickel is not that rare, so iron-nickel or cupronickel alloys might be possible solutions also. I doubt anyone would invent that without having metallurgy good enough for steel though.

There is also similar "telluric iron", if you dislike gifts from heavens.

Wood

Bamboo for example can be hardened to make decent knives and good spears. While metals are usually better you can actually make weapons and armor from wood.

And the superiority of metals is only an issue if your opponent actually has metal equipment. For building a setting it isn't that big a deal. As long as you remember the limitations that not having iron tools would cause for agriculture, masonry, carpentry, and the many other things that were transformed by access to cheap metal that keeps an edge.

Glass

You can in theory make weapons and armor from glass. It just doesn't make any sense if you have access to metals. The big issue is the brittleness. Glass has tendency to shatter on hard impact. This is not a good feature for a weapon or armor.

The simplest solution should be to laminate it with a material that prevents the cracks from spreading. Brass, bronze, copper, silver, gold, or their alloys should all work if the the layers are thin enough. Note that you do not need lots of the metal. Also note that actually manufacturing such a blade would almost certainly be a major pain. It really does not make any sense if you can use bulk metal instead.

Although a glass-gold laminate sword would be pretty cool... And would have the corrosion resistance to be a "sacred relic" for a very long time. Probably could outlast the species that created it. In a fantasy story a sword that was created at the dawn of time and has been sacred to multiple dominant species as they rise, flourish, and finally go extinct might be nice story item.

You'd probably want to make only the edge of the laminate and the rest of the weapon from wood in construction similar to what the Aztecs used with obsidian. Although the laminate would be more durable, so you could use a single blade instead of multiple microblades.

It never makes sense to make glass armor pre-modern since you can use wood, horn, hardened leather and cloth armor instead. The composite structure needed is just too complex without modern technology.

Stone

You can make weapons and armor from stone as there is really a wide variety of stone. Invariably they lose to metal in the ease of working them into durable forms. But if metal was unknown or unavailable and suitable stone was common it might happen. Or perhaps only swords made from jade can cut the demons and jade armor protect from their corruption...

Still stone can be used in combination with other materials to make effective weapons and armor. Essentially the other material supplies forms and resilience while small stones attached or embedded supply the hardness. Concrete is actually such a composite with different goals. Such weapons and armor are practical but require lots of work and maintenance.

As I mentioned before the Aztecs had a "sword" with small obsidian blades forming a cutting edge. It was fairly effective until it hit metal armor...

Summary

Of the above the meteoric iron is probably a usable answer. Bronze alloys, wood, and stone fall into the category of "good to know and might be of marginal use sometime". Like I said, this is kind of an extended comment that does not fit as a comment. The glass section is just a curiosity. It is probably too complex to be invented by a civilization that actually needs it. But if you want something really weird that comes from the distant past or a really exotic race...

Answer 4

A trio of things for a dangerous combination would be Brass, Bamboo, and Laquer. Add Resin to the mix, and you have a powerful set of tools for laminate armory and weapons.

Event early iron would have trouble competing against this combo as the flexible bamboo would help the brass keep it's shape, thou not the edge. Hardened Resin and Laquer could be honed to a sharpness close to glass.

Reinforce the back edge or center with bamboo, coat the edge in Laquer , and hone to sharpness.

(Would provide links, but working from phone. Laquer was used in Ancient China both as a clear seal, and tinted. It was derived from some kind of sap.

Resin was another sap based material that the Viking and Celtic cultures used for sealing boat and ship hulls.)

Answer 5

Comments here have mentioned Nickel, but another excellent candidate would be Manganese. Manganese is added in small amounts to many steels, but if you make it from 12%-15% of your mix, you end up with Manganese Steel, also known as Hadfield Steel. Manganese, and to an extent Nickel as well, can allow steel to remain in its Austenite phase at room temperature.

Austenite steel is fundamentally different from the steel you're likely used to. One weird quirk is that it's not even magnetic. Normal carbon steel only turns to Austenite at over 727C. It is significantly softer than ordinary steel, but also significantly tougher as a result. For an added bonus, Mangalloy steels are incredibly work-hardenable! This means the more you hit them with say, a hammer, the harder the surface gets! This allows for armor that has a hard surface layer, with a tougher under-layer.

Hadfield steel was the first steel discovered that behaved fundamentally differently from carbon steels. Before it, one had to choose between hard but brittle high-carbon steel, or soft but tough low-carbon steel. While there may be better elements to add to your steel armor than Nickel or Manganese, for instance Molybdenum, both Nickel and Manganese can be extracted from their ores by smelting in a manner similar to Iron. The elements are even often found nearby! If you still have trouble finding a good vein, balls of the stuff just grow on the ocean floor. (Hope you know a mermaid!)

Of course, knowing little about Manganese your Medieval people would not know about its properties, even if the technology needed to produce it is simple enough.

Answer 6

Metal is meh. Least as far as armour goes. Composites are probably far more useful, and yes, you could make decent composites with horse glue and cloth.

There's a few possibilities for useful, exotic materials that would have been available to medieval folk, either in conjunction with or instead of regular materials.

Layered fabrics with glue in between would likely have been useful against stabbing and slashing weapons. While the variant that came to mind was the Greek linothorax. However while the Greeks used linen, silk might be a useful fabric here - done correctly it's bulletproof and the Mongols used it as part of their armour. I'd suspect rather than a single material, a mix of materials and layered armour, would work well.

If we wanted to go a little nuts, maybe domesticated spiders for super strong silk.

As for weapons, once again, there's interesting options that are not metal. Obsidian made good sharp blades, and I suspect that whole glassworking wasn't quite to modern standards, even crappyish glass could be sharpened into something stabby or slashy, maybe used like the a Macuahuitl or Tepoztopilli

Answer 7

Something that I don't think has been addressed thus far: Steels!

Medieval steel, while good for its time, isn't that great compared to more modern steels, since it was little more than layers of carburized iron; very labor-intensive to produce, since it requires a skilled smith who knows exactly what he's doing.

It's possible that your Medieval-equivalent society has developed better steel-making techniques; perhaps crucible steel (first patented in Europe in the 18th century, although present in Asia for much longer) has made an early appearance.

Answer 8

Since other non-metallic materials were brought to the subject, you have different fibers that are protective; e.g., cotton, especially against bludgeoning damage, but also piercing if specially manufactured. But even better is hemp fiber, from which bulletproof clothes are made today.

You have copper/gold alloys that were made for mining in cultures with little or no steel metallurgy knowledge (Incas) and for armors for its toughness (Korea).