Anybody using bismuth shielding alloys?

[Typecaster]

Just got an option on a pile of bismuth alloy ingots, marked as certified radiation therapy shielding alloy. There are two specs, but unfortunately the ingots aren't marked.

MT-A203—bismuth 52%, lead 30%, tin 18%. Melts at 203ºF.

MT-A158—bismuth 50%, lead 26.7%, tin 13.3%, cadmium 10%. Melts at 158ºF.

I'll cross my fingers and hope it's the one without the cadmium, but that should be easy to check by the melting point.

Has anybody played with this stuff already?

[Morgan Astorbilt]

Wow, A while back, I bought, from a fellow shooter, a radioactive imaging technician, a dozen "Lead"? radioactive imaging generator containers, shaped like footballs, and weighing 30lbs apiece. The plastic carrying containers are marked: Bristol Myers Squibb Medical Imaging TechneLite Technetium Tc99m Generator. And in smaller letters on a label: Molybdenum Mo 99-Technetium Tc 99m Generator.
I recently hardness tested, the "lead", and it came up about as hard a Lyman #2. I wasn't aware that they used metals other than lead for radioactive shielding, the 1/4" lead plate shielding X-ray rooms, has always been pure lead. I'm going to contact Squibb and ask.
Morgan

[Typecaster]

Morgan—
As I understand it, this stuff is used to make custom radiation shields, not as in the shielding in the walls of the room. I guess it's like if you have a tumor in your left n*t, somebody gets to take a cast, make a mold from that, and make a custom radiation shield to protect the good one and the rest of the equipment from getting zapped. Kinda like an airbrush frisket...

It's happy minutes now, but I'll see at what temperature one of the ingots melts later tonight. If it's the alloy with cadmium, the project stops; otherwise, I'll probably buy a couple hundred pounds to experiment with.

[Ricochet]

Reckon they just pour it around your n*t at 158-203°F?

[Ricochet]

What this stuff ought to really be great for is making chamber casts.

[Typecaster]

Test results: placed ingot in a pan of water and heated it up...bottom of ingot was making a very pretty silver puddle when the digital thermometer showed water temp of about 160ºF. Bad news, probably...this is the low-temp alloy with cadmium. I called the foundry and requested a MSDS.

It's an eutectic alloy, equivalent to Cerrobend from Cerro Metal Products, which is also called Wood's metal, bend alloy, or Lipowitz metal in Europe. Brownell's says Wood's metal is bad news for chamber casts, Ricochet, because it expands slightly when cool. It's used as a filler when bending thin-wall tubing—fill tubing with alloy, when the alloy cools the tubing can be bent without collapsing.

Wikipedia says it can be used for making metal inlays in wood, and is also called pewtalloy, but I wouldn't want to use it instead of pewter until I study the data sheet. Containing cadmium, you gotta wonder at what point a stockpile becomes a Superfund site.

[Ricochet]

Might be interesting to experiment with as an additive to lead. Bet it works as a hardener, probably responding to quenching and aging. Most alloy additives have a low solid solubility in room temperature lead. I'm pretty sure cadmium was on that list of precipitation hardening additives in the old Key to Metals article, and I'm sure bismuth works.

I'm really not too concerned with the toxicity if I'm not heating the stuff enough to volatilize it.

[Typecaster]

OK, Ricochet, you've got yourself a project. I'll be happy to send you an ingot to experiment with; if you want more, there's probably another 150 lbs or so. PM sent.

Here's a link to some info on the stuff: http://www.harpellassociates.com/medtec/medical-physics/custom-blocking/consumables/mt-a158.asp

BTW, the same alloy, under the Cerrobend name, is over $42 per 1.5-lb ingot at McMaster-Carr.

[Ricochet]

Well, that is interesting. I'd like to give it a whirl. Worst I can do is mess up a pot of soft lead, of which I have plenty.