To much Antimony

[HeavyMetal]

I read on one of the threads here that more tin than Antimony was detrimental to the alloy.

For the life of me I can't find the post and don't remember what the side effects were when tin content exceeds that of Antimony.


Anybody else seen or read this post? If you have please post the answer, I have a beginer with a bunch of reclaimed shot and a lot of Tin and I'm trying to convince him that 7% Tin and 4 % antimony is not a good idea.

He's got it in his head that he can do better than Lyman's 9-5-5. I'm hoping to convince him that "lite" Tin alloys are better.

[randyrat]

I read it also...So much for my memory.... I thought it was the other way around More Tin than Antimony was detramental

[Rocky Raab]

Well, you just read it wrong again - that IS what he wrote.

There's no convincing some folks about some hare-brained idea they have. You can quote centuries of experience by experts, and the buffoon will cling to the idea that he's discovered the "Great Cosmic Secret" that runs opposite to conventional wisdom.

Afterwards, just smile and remind him that convention and wisdom go together for a reason.

[montana_charlie]

I read an article addressing this question (among others) on LASC.

The information was...
Antimony can harden lead, but it is a 'brittle' hardness.
Tin has only limited hardening capability, but causes the alloy to be 'tougher'.

It's like adding antimony is the hardening stage of making a spring from steel, and adding tin is the process of drawing the temper...which makes the spring flexible while still being hard.

The author said that antimonial brittleness starts to become a problem when the amount of antimony exceeds the amount of tin by a certain percentage.
I believe (because I can't find the article now) that tin needs to equal at least half of the antimony content.

That 90-5-5 alloy would be hard to beat by adding more tin.

CM

[HeavyMetal]

Randyrat didn't read my original post wrong I had to go back and edit the post because I got the tin and antimony switched in the text!

My Bad! So I did the edited version everyone else is now seeing.

I will go check out the LASC site. If additional "brittleness" is the only issue he's gonna have I may let him have at it.

I could have sworn I saw a warning about another issue like poor or patchy fillout, porosity and air voids that kind of stuff.

He's thinking he can come up with a "wonder alloy" I'm just trying to keep him from jacking up 400 pounds of shootable material

[outdoorfan]

Although I have no experience with it firsthand, I think I've read that more tin than antimony will annul or severaly limit the heat treating capabilities of the alloy. I don't see how it would make it less cast friendly, though. Tin is your friend there, me thinks.

[Matt_G]

Why in the heck would he make 400 lbs. of that alloy before he's seen whether or not it will perform like he wants it to? :roll:

[BIG GUN]

Linotype is about the best mix for good casting and hardness. Tin allows a better flow/fill of a mold but to much creates solder and drops the melt temp to a point of causing leading of the bore.

[KYCaster]

....Tin allows a better flow/fill of a mold but to much creates solder and drops the melt temp to a point of causing leading of the bore.


There's something I've never heard before. Have you experienced this yourself?

Just curious.
Jerry

[runfiverun]

tin likes lead but it loves antimony, if you have more tin then antimony
as the alloy starts to cool the tin doesn't have time to rebond with the lead as the longer chain of sn is torn fron the shorter chain of sb.
now that leaves spots of tin not bonded with either element causing spots of tin surrounded by spots of softer pb which is where your problems come from
so his 7%sn 4% sb alloy is gonna cause him problems and waste his money [more of it by the way when he leads up his bbl]
2% tin will do all he wants and needs.

[HeavyMetal]

Thats what I was looking for!

Thanks RFR Now Maybe I can get him to understand what he's really making is an alloy that will lead terriblely because of soft spots in the finished product!

As for the reason he'll make a 400 Lb batch? Guess thats my fault as well as we had discussed "custom" alloys a month or so ago and I mentioned the fact that the bigger the "Batch" the more consistant the alloy would be as you cast it into usable ingots!

Thanks guys!

[geargnasher]

IIRC the article at lasc.us (or maybe it was the Lyman Cast Bullet Handbook) mentioned the benefits of tin/antimony percentage come from the way tin and antimony form their own intermetallic compound of SbSn when mixed in certain proportions and the alloy then reacts as a binary of Lead and SbSn.

When one upsets the balance of SbSn with too much tin, the alloy isn't "eutectic" anymore and components freeze at different temperatures and that's detrimental to casting.

Linotype is eutectic because any extra antimony will freeze at the same temperature as SbSn and lead. Lyman #2 was chosen because it maximizes the potential of the SbSn bond with the minumum of expensive antimony/tin. You get a tough, hard alloy that is heat-treatable to an extent and casts very well.

If you use WW, you get, say 4% antimony and then you add 2% tin for castability, you get basically 4% of your alloy being SbSn, 2% being unbonded Sb, and the balance pure lead and trace elements, basically a eutectic alloy. If you add 4% tin, you would have a better SbSn percentage and tougher (but not necessarily harder) boolits, but if you added 6% tin to your WW you would no longer have a eutectic alloy as the extra unbonded 2% tin would freeze separately and you would have a structure of lead with antimony/tin and separate tin pockets in it that may affect surface strength and casting defects.

Clear as mud?

Gear

[runfiverun]

the 4-5% area is also the point where things seem to go backwards and you lose toughness and start to just get brittle alloys.

[shotman]

antimony in the pure form looks like crystals and will shatter into a thousand pieces.when hit with a hammer. It also has to be very hot to melt. I have made some pure boolits . They didnt shoot good . I dont know if they came apart as Iwas shooting at cans ,and the cans were safe