I received some ingots cast from a LEE ingot mould. I do not kbow the alloy composition. I do know the eutectic temperature of the alloy is 570 degrees, is there any way of determining the composition based on this info?
Thanks
Aaron
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I received some ingots cast from a LEE ingot mould. I do not kbow the alloy composition. I do know the eutectic temperature of the alloy is 570 degrees, is there any way of determining the composition based on this info?
Thanks
Aaron
If the alloy is a eutectic it melts all at once - there is no mush stage in which one phase is molten while the other is solid. The only lead-tin-antimony eutectic with sensible proportions of tin and antimony is linotype which melts at 462 degrees F. I don't think you have a eutectic, unless it isn't a lead-tin-antimony alloy.
I heated then alloy to 700 degrees, then shut off the heat source. I measured the temp every minute. It dropped around 15 degrees per minute consistently. When it hit 570 degrees, it stayed exactly that temp for three minutes, then I pulled my thermometer so I would not have to reheat it to take it out. The alloy was not slushy and semed like it was eutectic . Bill Ferguson mentions other eutectic alloys in his website, so I thought maybe the were others he did not mention.
Thanks
aaron
Yes, there are definitely others. It prolly takes a magician who could decipher each and every one because of the various "impurities" involved on a quantity basis. ... felix
What makes an alloy be eutectic?
Aaron
A eutectic alloy consists of a single "phase" - in practical terms, it has no liquidus phase when melting, but transforms from solid to liquid at a single temperature. For a simple lead-tin alloy, that happens if it is 63% tin and 37% lead.
Lead-tin-antimony alloys in the under-20% range for both tin and antimony have as one phase, an alloy containing 4% tin and 12% antimony which melts at 462 degrees F. If they are at any temperature above 462*F they have one molten phase, so that is their solidus temperature. Their liquidus temperature, at which the remainder of the metal becomes molten and hence the entire potful ceases to be mush, depends on what is left of the alloy after as much as possible of it is taken up as the 4%-12%-94% phase. As you probably know, 4%-12%-94% is actually pure linotype; for any of these ternary alloys the linotype content melts first when you heat them. The remainder can have any melting point up to pure lead; it just depends on what that residue consists of. Thus electrotype, sometimes called Taracorp Magnum in the US, consisting of 2% tin, 6% antimony and 92% lead, has a solidus temperature of 462*F like all such alloys, but its liquidus temperature happens to be 534*F. As you raise the tin and antimony content the liquidus temperature decreases until you get to linotype composition (4% tin, 12% antimony) which is the eutectic, so solidus and liquidus are identical at 462*F. If you keep raising tin and antimony contents the liquidus rises again, and by the time you get to foundry type (12% tin, 23% antimony) the liquidus temperature is all the way up to 620*F.
Because these alloys are ternary (they consist of three different constituents, not two as in a binary alloy such as solder or Lyman #2) their phase chart is a three dimensional plot. It contains a "eutectic trough" defining the limit for the formation of primary lead crystals in the solid solution. As well as passing through the linotype composition, this trough passes through 10% tin, 10% antimony which melts at 476*F and technically qualifies as a pseudo-binary eutectic. It is not a ternary eutectic - linotype is the only one of those.
So, your alloy might be a pseudo-binary eutectic (the 10%-10% alloy is the Sb-Sn pseudo-binary, there could also be Pb-Sb and Pb-Sn pseudo-binaries). If you are sure it behaves like a eutectic (no sign of even a tiny difference between solidus and liquidus) one possibility is that your thermometer is inaccurate and you have the 10/10 pseudo-binary eutectic.
I am sure my thermometer is correct. I checked it with known linotype and it was within 2 degrees. I hurried with this unknown alloy today because i had little time. I suppose what I am trying to do by measuring the temp is not going to tell me anything anyway. If I actually had a mold to cast some bullets yet, I could try to determine its specific gravity. Oh well
Aaron
""If I actually had a mold to cast some bullets""
I get scrap stuff all the time. I drove myself nuts with the whatsits. The bottom line is how does it cast ,how hard is it, and how much do you got.
or you can go to a salvage yard ,many of them have a tool to determin the whatsits in alloys......Buck
Aaron, the melting temperature does tell you something, it just doesn't tell you enough on its own. The density would tell you something more, as you say. The hardness would be another clue. Unfortunately all three of those together may not pin it down, though, if it is highly alloyed. If you get a mould you could not only measure density - you could also make up samples both with and without heat-treatment, and their hardness would give you a fourth datum.
I love my hardness tester. Have I ever said that before? :grin:
nope! :D
Are you sure it is an alloy? Pure metals behave eutectically.
I cannot think of one that melts at 570 though !
Jerry
Bass I agree with you (I seem to recall it was mainly on your advice I bought mine, too) but there is a problem with alloys suffering from tin depletion, as you can see from the chart IMASHOOTER2 posted in this thread:Quote:
Originally Posted by Bass Ackward
http://castboolits.gunloads.com/showthread.php?t=14971
If the tin content is only 2%, the hardness stays the same from 12% antimony up to 24% antimony, and it can be difficult to tell what you have except by cheating: adding another 6% tin and seeing what the hardness increases to. I have some tin-depleted foundry type and am pretty much in that situation.
Quote:
Originally Posted by grumpy one
I .... don't .... use a hardness tester that way anymore. But that is a good chart. At least it is accurate from what I have experienced / tested over the years.
At this point in my life I care less about what a mix is. Or what it might be ...."If". I .... just .... want to know how hard it is now so I understand how to .... positively push it, cause it's going up the pipe one way or another. And the less guessing I need to get a good load, the more there is for actual blammin. :grin:
Bass, I think there are things that you just wouldn't do because of your experience, whereas we dumb bunnies might blunder right in. My tin-depleted foundry type tests at 19-20 BHN air cooled, and casts like water with wetting agent added, but it probably has large amounts of free crystalline antimony in a matrix of linotype. In terms of abrasive characteristics, and brittleness as well, this is probably not a good shooting alloy. I fired just a couple of hundred of them through my 30-06 and could measure several thousandths increase in the bullet seating depth to just engrave, even though the rifle is a milsurp with a lot of use behind it. It's kind of a firelapping alloy.
Obviously I don't plan to shoot more of that alloy without adding a whole lot of WW to it, not least because it is extremely unfriendly to my Lyman 45 lubesizer. Getting those hard bullets back out of the sizing die often had me muscling the lever so hard that the whole 200-300 pound steel workbench was pogoing around the shop like a skateboarder on speed. I suspect Hornady gas checks were harder to get out than Lyman ones, by the way.
This alloying thing is fairly easy to manage if you want what most bullet casters want: a cheap consistent alloy at about 14-15 BHN. My year-old WW ingots are 14.9, so I don't really need to add anything but tin unless I want to avoid the wait between casting and shooting. However, where is the fun in that? I need new frontiers, every day, and I certainly don't want to admit that I wasted my time and money putting 300 pounds of foundry type ingots under the bench.
You really need to keep recording temperatures until WELL past the flat. But, that said, this does sound like a eutectic. Probably pure lead. Thermometers can be off. You could calibrate it, of course, but my guess is that if you ran this same test with pure lead you'd get the same curve. I think lead freezes at 600+. Don't remember the exact temperature but for an inexpensive thermometer it could be off this much.Quote:
Originally Posted by Aaron
The abrasiveness quits when all the antimony is "covered" by the tin in the mix. So, the alloy 94-3-3 would be "smooth", and so would 90-5-5, etc. Throat wear would still depend on the powder blast. More powder, more blast. Faster powder, more blast. ... felix
Quote:
Originally Posted by grumpy one
No. Can't be. Please take it back before someone reads your post.
You just ruined your reputation. Just 200 rounds and your throat lengthened? I tell people all the time what antimony will do and they tell me I am crazy. They believe lead is lead and you can shoot it forever with no chance of changes to your throat or bore. :grin:
Just lubricate that mix with LLA and you have a faster cutter than 600 grit! :grin:
I didn't realize that you wanted to shoot hard stuff like that. Whole new ball game. I water drop or HT to get hardness now if I need it. Anything to keep down the erosion. But in truth, 15 BHN will do just about anything I need.
I fire lapped a revolver tonight with 220 grit on TaraCorp alloy (15 BHN). It usually leaves furrows down the pipe that look like inverted rifling. I ran 24 rounds through from old WW which are 9% antimony coated with LLA. Just finished cleaning and I can't tell that the 220 grit was ever fired. Bore looks like the mirror surface of a calm lake.
Love those non-lubricating lubes for smoothing for sure.
Bass and felix, you've raised an interesting question now about how bore and throat erosion happens and how it can be treated. I have a 30-30 with a corncob-like bore, which is microgroove and way, way oversize. If I shoot a bunch of tin-depleted foundry type I might reduce the roughness, but I also might end up with even shallower and more-blurred rifling than I already have. I also have a milsurp 30-06 that has a .310 throat with enough pitting so that a slug measures .311 in places. So, a little tin-depleted foundry type sized .311 or .312 might reduce those pits, but it might also cut a new throat which is off-center to the bore.
Any suggestions?
Grumpy, you already know what we would tell you, and, unfortunately, as BA says you have to let MrGunn tell you when to quit messin' with him. ... felix