Unusual alloy of gold and steel

[2square]

Hi everyone,

I was wondering if somebody might be so kind to help me by answering this question-

Is it technically or theoretically possible to create an alloy consisting of 90% pure (24k) gold and 10% steel?
If it were forged in the right conditions, could this combination result in a true alloy?
Or would the mixture end up as a non-homogeneous compound no matter what?

Many thanks for your help.

-George

[Frosty]

Jim Binion makes iron gold mokume gane using powders and sintering the mixtures. Is it a true alloy? You'd have to ask Jim.

What do you have in mind for an alloy like this? While not a metallurgist by a long shot I do know alloys often have results that are very much counter intuitive.

Frosty The Lucky.

[Irondragon Forge ClayWorks]

Welcome from the Ozark Mountains. I remember that being discussed in the past but haven't searched for the threads. If you search like suggested in the Read This First thread it should show up.

I can't control the wind, all I can do is adjust my sails.

[2square]

Thank you Frosty and Irondragon for the replies.

I'm not even close to knowing anything about metallurgy. I am a writer working on a script for a BreakingBad-style of story and I could use some expert advice to help me square a circle in the story plot.

In the plot, stolen bullion is accidentally dropped into a large crucible which is being used to make steel. Since the temperature would be pretty high (melting iron) I would think the gold would melt fast and I was wondering if this would create a homogeneous alloy or just layered patterns as Frosty mentioned.

 

 

[Ferritic]

The equilibrium solubility of iron in gold is very low at room temperature, e.g. less than 1wt%. However, it's solubility is greatly increased at higher temperatures. Going from the phase diagram, I suspect, if you were to quench at a sufficiently great rate, from 900C, you could retain a non-equilibrium alloy of 10% Fe in gold. Not sure what quench rate would be required and, of course, if you were to heat the alloy moderately, it would decompose into a two phase material (alpha Fe and gold).

[2square]

Thank you so much Ferritic for your informative reply.

To clarify, let's say the process went something like this- 

A small blast furnace running at somewhere between 1500-1700 C contains some leftover Fe and C from a batch of ore that was being used to make steel. Solid gold is dropped in, resulting in a (approximately 10% Fe, 90% Au) mixture at the bottom. The gold fully melts and mixes. Then the mix is poured directly into casting molds without quenching. The material in the molds is then allowed to reach equilibrium through gradual cooling.

If I understand your comments correctly, this would mean the process described above would likely produce a two-phase material, but not a truly homogeneous alloy, and there would be no coring. Does this conclusion seem reasonable?

And if you were to heat up the material again, as you mentioned, it would then be possible to extract the Au from the Fe and C and other impurities. Correct?

 

[George N. M.]

OK, I see a couple problems with your scenario.  First, if you dump a bunch of solid gold into molten pig iron (that is what blast furnaces make.  It is further refined through several possible processes to make steel) the solid metal will cool the liquid metal pretty quickly and you would end up with large chunks of gold cemented together with an iron matrix.  There would not be enough heat in the molten iron to melt all the gold.  Second, you would have to agitate the liquid in some manner to get the two metals evenly mixed with each other.  Without that the gold would sink to the bottom and and the iron would float on top.  At best, you might get a "marble cake" swirled effect. 

To be realistic you would have to figure out how much molten iron (2800 degrees F) it would take to melt X amount of gold (melting point 1980 degrees F).  And don't forget that iron is weighed in ounces and pounds Avoirdupois  and gold is weighed in Troy ounces. 

Even if you were to get the two metals evenly distributed in the melt as it cools it seems to me that because they would not actually alloy/chemically bond, gold is VERY non reactive, reheating to a molten state would allow the iron to float to the top and be poured off like the slag in a normal blast furnace melt.

A 10% Fe, 90% Au would just be an impure (about 21.6 karat) gold mixture.

BTW, blast furnaces are pretty obsolete today.  What iron is produced from ore (most is derived from scrap) uses basic oxygen furnaces.  I'm not sure if there are any blast furnaces still operating in the US today.  If there are it is only a few.  Also, there are no "small" blast furnaces.  They have to be of a certain size to be economically viable.  Even the smallest that was in operation, say 75 years ago, was still hundreds of feet tall and would produce tons of iron in a single melt/charge of ore, limestone, and coke.  Blast furnaces also produce a lot of carbon monoxide and CO2, some of which is recycled into the furnace but they are still pretty "dirty" in terms of producing green house gases.

I grew up on the South Side of Chicago within sight of the US Steel South Works and worked there and at Inland Steel in East Chicago, IN for 3 summers in the mid '60s.

"By hammer and hand all arts do stand."

[Frosty]

Writing a script eh? If it's for Hollywood then accuracy isn't important. How much bullion, enough one or two men can run carrying it?

I can work with that. Forget a blast furnace, especially a running one it's be close to fatal for unprotected men to get close enough to throw anything it let alone "dropping" it in. 

Okay, try this. The bandits (or whatever) have escaped the repository where the bullion is kept or being moved or whatever. However the guards and cops are in hot pursuit and they're managing to keep ahead but can't shake them. 

Scene change to a metallurgical research lab where a new aerospace alloy is being developed. The crucible is charged and ready for the vacuum electric resistance furnace for attempt 42 in the series. 

As the bad guys come dashing down the side street having ditched the car and looking for another one to hot wire and continue the escape. Well ahead they see police cruisers passing on a cross street and the sirens of the ones following grow closer and they're cornered so they pick a locked door and dash inside. Unfortunately it's not a good hiding place, there are walls full of equipment and all sorts of computers, screens, etc. and one window. 

The sirens come closer and the bad guys are starting to panic. the head bad guy says that because nobody actually saw them they can walk away if they can hide the gold. One of the others looking through the window sees a tech in a lab coat putting small ingots in a large black jar so they put on lab coats slip in one of the doors and place the bullion under some of the other ingots in the crucible. Then they slip out, take the lab coats off and walk out the door to the street where the cops look them over, ask a couple questions and go back to their search.

Unknown to the bad guys they'd tripped an alert when they opened the side door but there were no cameras to record what happened so security installed a dead bolt that can only be unlocked from inside and a surveillance camera.

In the mean time the metallurgists begin the test melt. It's an alloy of steel, chrome, nickel, platinum, iridium, copper and a smidge of unobtanium. In hopes it will serve some extra high stress purpose in space. (Be VAGUE about these kinds of thing!) Throwing around some convincing sounding terms and stuff works well though. The alloy has to be an amorphous alloy with eutectic properties causing it's liquidus to be much higher than any of the metals in it AND be mechanically as strong as high carbon steel. 

The melter operates under vacuum to prevent contamination and oxidation, the melt is stirred constantly electromagnetically and when it reaches the exact temperature the magnetic field crushes the stuffings out of the alloy while it cools. 

And THERE you have a TV script process for producing B.S-ium alloy.

Hmmmm?

It's not an accident that black smithing and bull shooting are abbreviated the same way.

Ah HAH there's my buddy George typing at the same time I am making all the points necessary to illustrate why you need a stronger dose of  B.S-ium on the page!

Frosty The Lucky.

[George N. M.]

Jerry, great minds think alike.  I like your scenario but a subplot might involve the resulting alloy having VERY unexpected properties that the researchers can't figure out becuae they don't know that gold was added to the mix and no one thinks of analysing a sample because they already know what went into it.  A nice twist of irony would be that the resulting alloy is many times more valuable than gold. 

GM

[2square]

Huge thanks George NM for calling out some of the biggest godawful flaws in my hare brain scheme. Having an expert finding faults in the story premise is not only super valuable -it's the only way forward to get to a workable plot that I can use.

And also thanks to Frosty. I got a got a kick out of your plot -you have a very active imagination.

Please understand that the idea is not set in stone. The process to obtain the contaminated cast ingots doesn't have to go down the way I wrote. I was just throwing it out there, see if it sticks. It's fiction after all, so anything can happen, right? The thing is I cannot go off the rails too hard. I still have to make this bit somewhat believable, or I won't be able to use it at all. I can certainly make it improbable, but not impossible.

So back to the drawing board. I have to work with the following constraints in the story:

-It happens in Europe in 1944. So no modern furnace tech will do.

-Whatever the process, it somehow has to start with 24 karat bullion bars and end up with the production of cast gold ingots with purity degraded to around 21 karats. The compound doesn't have to be 10% Fe, 90% Au (the steel mix was just an idea). But the new ingots must contain a distinct (preferably unusual) combination of impurities that act as a sort of unique fingerprint. This is something that will help identify the provenance of the gold later in the story.

-The contamination in the re-smelting process of the original 24k gold ingots cannot be a willful act. It must be the consequence of an unintended action at the foundry. Something like a mistake, sabotage, or some kind of oversight or accident (you can leave these details to me, Frosty). 

On the other hand, I'm free to end up with whatever product you might think possible -a homogeneous alloy or some very different compound (a two-phase material?) -anything, just as long as the ingots can be later reheated to extract/refine the gold.

Perhaps my original idea can be improved? Or maybe it's just so bad it cannot be salvaged. Maybe got to find a completely different way to get to the intended result. Unfortunately, I don't know a thing about furnaces, or metallurgy or alloys.

I really appreciate your creativity. So if you can cook up a better idea of how to end up with the contaminated ingots, please tell.

[Frosty]

Don't they just George, don't they just. Wouldn't we make a fine pair of plotters?  

I had to stop typing, I kept thinking of more twists, I was having too much fun. Writing science fiction has been a hobby of mine far longer than blacksmithing.

Don't worry 2square we understand brainstorming ideas, often an idea thrown out doesn't stick but triggers another idea, that's how it works. I'm also familiar with the difference between the suspension of disbelief and true, it's the fundamental principle of good fiction.  

Knowing the time period makes a big difference. Where does the melt happen?  If Germany then you can easily slip more modern tech into the story, have it happen at a Krup research foundry, they still make some of the most advanced steel alloys in the world. electric resistance melters have been around almost since Ben Franklin and a controlled atmosphere is old tech too. 

Germany had a secret research facility in Peenemunde from 1936 to the ed of WWII when the allies finally successfully bombed it with some of the first deep penetrating delayed detonating bombs. Then the allies took everything of interest and the scientists home starting the "space race" and more. Even in 1944 it's perfectly plausible that Krup or another foundry was using advance tech developed in the rocket labs of Peenemunde. German steel tech was a source of intense avarice all over the world so finding some anywhere is plausible. Say a German metallurgist needed to get his family out of Germany and traded some steel tech to pay for it. Hmmm? It's just a detail in the story you only need to hint at.

Engineering an accident that allows the thieves to hide the bullion where it ends up in a melt undetected is as easy as a couple few re-writes to refine the idea. Heck, the rocket metal guys may have been experimenting with gold bearing steel alloys so wouldn't think a thing of it if they'd noticed at all. In 44 things were extremely frantic at Peenemunde, Hitler was looking for a magic bullet to win an already lost war and launching rockets against his enemies was a last straw. There's nothing like a do or die order from the raving lunatic in power to stir folks to ignore little things like strangers in an industrial area, strange ingots, etc. when everybody is rushing around like a cat with it's tail on fire.

I have nothing more invested in brainstorming this than the fun I have doing it so use an idea or not is no skin off my bucket of oysters.

Frosty The Lucky.

[George N. M.]

another plot twist might be that the gold is introduced into the metal as an effort at sabotoge by Jewish/Russian/Polish/Roma slave laborers.  Perhaps by a Jewish metallurgist/chemist who figures he can mess up an experiment and deprive the Nazis of valuable gold at the same time.  The Nazis were using LOTS of slave labor to procude high tech weapons late in the war.  Most of the V-2s were made using slave labor.

Also, the gold might have a Nazi connected origin story, e.g. melted down wedding rings, etc. from the concentration camps.

GNM

[2square]

Frosty nailed it: what's needed here is just enough realism to allow suspension of disbelief. If the technical aspect of the premise can somehow pass muster with you guys, it will definitely be ok with the general public.

I really like GNM's idea about sabotage. I can work with that.

Here's some more info that might help:

-The foundry is located in occupied Belgrade, Yugoslavia. No V1 rockets or German advanced steel tech there. This is a more primitive operation.

-The objective of melting the original bullion ingots is to destroy the hallmarks and recast the gold into a different number of them and with different shape. Can't say much more, but as you've probably guessed we're dealing with Nazi gold.

Need to solve these four fundamental problems:

1. What kind of furnace we might be dealing with, given the place and 1944.

2. What kind of compound or metal was added to the furnace after the ingots were thrown in (if sabotage), or what was already inside (if accident).

3. What proportion of added compound relative to Au would be needed to produce the desired 21k outcome. In my first iteration I thought 10% Fe was good enough. And as George said- 'To be realistic you would have to figure out how much molten iron (2800 degrees F) it would take to melt X amount of gold (melting point 1980 degrees F)'. But as I mentioned, the contaminant doesn't necessarily have to be iron/steel. You can pick whatever you think might work best.

4. What would be the temperature in the furnace needed to melt the Au and mix well enough with the compound of your choice?

Thank you for brainstorming with me and for hanging in there.

[George N. M.]

I think that if you are going for a 21 k mixture you need a yellow metal such as brass or bronze because the ingots will still be yellow/gold colored. But the ingots would be much heavier.   Brass melts at about 1750 degrees F, depending on the exact alloy.  Since brass/bronze casting has been around a LONG time you could set it in any old foundry which would not be using state of the art equipment in 1944.

You could also work in the gold being hidden in a cold/empty crucible with a charge of brass or bronze being added without the workers (perhaps slaves or prisoners) noticing or caring.  Then, a problem would be that the metal has been cast into door knobs or machine parts.

Since it is 1944 in the Balkans you could mix in Tito's partisans or other anti-Nazi guerillas or British or American secret agents.

If you have the gold derived from the concentration camps a hard core Nazi might guard it with less zeal because it was "Jewish" gold and somehow "tainted."

I can't help you on the type of furnace in use in a foundry or other industry at that time.

I hope you will share the finished product with us.  I know I would enjoy seeing it.

GNM

[Frosty]

75% gold and 25% iron makes blue white or blue gold.

A quick search hit on more info about gold than I'll ever want to know but if I read it, I'll have all these gold alloy factoids bubbling around my head any time gold comes up. It's the curse of having a near eidetic memory for the written word. <sigh>

Frosty The Lucky.

https://www.911metallurgist.com/blog/gold-alloys

 

[2square]

I'm having trouble finding a gold-iron phase diagram. Does anybody have one?

Thanks in advance.

[Frosty]

Oh come ON!  A quick search using those for terms hit on several pages to chose from. I love brainstorming your story but we aren't your research staff. 

Frosty The Lucky.

[2square]

Sorry, yeah, I was googling half asleep at 2am and I don't know what the xxxx i did to miss this. There's lots of them.

Thank you for all your help.

I made a donation to this forum website.

Edited August 12, 2023 by Mod30
Language

[Frosty]

Ah, sorry for the cross reply, you caught me in a grouchy mood.  

Frosty The Lucky.

[patrick]

Blast Furnaces-These are in fact still the predominate way of converting iron ore into pig iron. There are less that 10 still operating in the US but they are widely used outside of the US. The pig iron that is produced by a blast furnace is then further processed in a basic oxygen furnance (BOF). A BOF is NOT used when make steel directly from scrap metal. In that case and electrical arc furnace is used to melt the scrap metal which then has the chemsitry adjusted to make the desired grade. Since both the blast furnace and the electric arc furnace input heat into the process, I'm sure you could get the gold to melt. Dropping cold solid metal into a bath of liquid steel without adding additional heat to the system is not likely going to result in complete melting of the object dropped into the liquid metal.

For a steel works in 1944 you most likely would have been dealing with an open heath style system couple with a blast furnace. The blast furnace would have made pig iron that would have then been converted to steel. Open hearth is no longer used anywhere in the world, but was common back then. 

If you setting is more of a foundry than a steel mill, melding could be done via electric arc furnace or induction melting. The difference between the foundry and the steel being that the foundry just melts steel and pours that into finished shapes while the steel mill is converting iron ore into steel or scrap steel into new steel raw forms like bars and plates.

For the scenario originally described, a 90% gold with 10% of iron would like not have much color change from gold. It might have some, but you would not be able to "hide" the gold in the iron. 

 

[Buzzkill]

If I understood correctly, a key factor is the alloy having a unique composition that indicates it could have only originated in one place.  All 2square is requesting is a plausible (even if unlikely) set of circumstances in Belgrade in 1944 in which the gold was contaminated by other alloying elements in such a way that there can be no doubt as to its origin later in the story.

To me, the brass/bronze foundry scenario posed by George seems the most plausible way to achieve the desired result here.

[Frosty]

Yeah, this is for a TV or movie script so all that's really required is enough plausibility to support the audience's suspension of disbelief. 

After looking at a couple gold alloy sites (I linked one) I have to go with George's suggestion of bronze or brass as the camouflage because the "gold iron" alloy colors listed are various shades of BLUE. It'd be like trying to hide a peacock with the turkeys. Also almost everybody knows brass is the same color as gold so it's a natural and enough folk know bronze can be a yellow metal too so it works.

Frosty The Lucky.

[Mike BR]

It just occurred to me that jewelers use gold solders that are deliberately formulated for a color match.  Looking up the composition of those might give you some ideas.