How does the alloy composition affect its melting point?

[old_haidouk]

I've been experimenting with different alloys lately and I've noticed how differently they behave based on the composition. Can anyone enlighten me how Tin and Antimony affect the alloy melting point and cast temperature?

[462]

I can't, but the 3rd and 4th editions of Lyman's Cast Bullet Handbook have extremely informative metallurgy chapters, written by metallurgists, that include temperature/alloy compostition charts.

Oh, the handbooks are the best source for published cast load information, as well.

If only more casters would buy one or more, and read them at least twice . . .

[MBTcustom]

Tin makes the melt liquid at a lower temperature.

[bumpo628]

This info is from a sticky in the alloy forum:

621° = lead
563° = solder (10% tin & 90% lead)
529° = solder (20% tin & 80% lead)
504° = solder (30% tin & 70% lead)
464° = solder (40% tin & 60% lead)
428° = solder (50% tin & 50% lead)
374° = solder (60% tin & 40% lead)
362° = solder (63% tin & 37% lead) (eutectic)
365° = solder (70% tin & 30% lead)
392° = solder (80% tin & 20% lead)
421° = solder (90% tin & 10% lead)
450° = tin

[Southern Son]

If you cannot afford the Lyman Cast Bullet book (I don't know how much they are in the US, but mine cost me $65.00 here in Oz), then look throught the stickies in the Lead and Lead Alloys forum. The effects of Tin and Antimony are not only being felt at the melting stage.

[MtGun44]

Look up a "tin-lead phase diagram" on the web, or in the Lyman manual.

Bill

[ku4hx]

I've been experimenting with different alloys lately and I've noticed how differently they behave based on the composition. Can anyone enlighten me how Tin and Antimony affect the alloy melting point and cast temperature?

+1 on 462's advice; no better "layman's" source for your question. And the rest of the data in the manual is excellent too. Every boolit caster should have this book in their library.

[303Guy]

Have a look at this link;

http://www.lasc.us/CastBulletAlloy.htm

[LUBEDUDE]

The melting point of Antimony (Sb) is 1167 f. However, when combined with other elements such as lead and tin; and depending upon the quantity of each, that melting point can vary considerably.
Why? I am not a big enough of a science guy to explain it at a molecular level, maybe someone else can.

I can tell you that in my 40 lb pot a 92 lead/6 Sb/2 Sn mix will start melting around 600 and will melt all the way through at around 630 give or take a few.

[Shiloh]

Tin lowers the melting point. It is also the priciest part of your alloy, and aids boolit fillout.. When first starting out, I would add tin instead of cranking the heat some. With tweaking the temp, I can get range scrap to fillout good and add a LOT LESS tin.

Shiloh

[Shiloh]

The melting point of Antimony (Sb) is 1167 f. However, when combined with other elements such as lead and tin; and depending upon the quantity of each, that melting point can vary considerably.
Why? I am not a big enough of a science guy to explain it at a molecular level, maybe someone else can.

I can tell you that in my 40 lb pot a 92 lead/6 Sb/2 Sn mix will start melting around 600 and will melt all the way through at around 630 give or take a few.

Hey, we don't need to understand the magic to appreciate it.

SHiloh

[sig2009]

If you cannot afford the Lyman Cast Bullet book (I don't know how much they are in the US, but mine cost me $65.00 here in Oz), then look throught the stickies in the Lead and Lead Alloys forum. The effects of Tin and Antimony are not only being felt at the melting stage.

Should have asked someone here to purchase one and ship it to you.