Making Ductile Cast Iron

Ours is granular..like small gravel. It has a mix of different alloys premixed from the vendor. I don't think you need to do anything but get the weight ratio right. I'm sure the smaller it is the faster it will go into solution but even 1/8 inch diameter chunks melt fine and go into solution within 3 seconds.

 

I would assume it's an alloy. Ni and Mg forms intermetallics, and these are usually brittle at RT. Casting and crushing/milling is much more effective than pressing powders. Powdered magnesium is an accident waiting to happen.

 

It comes in ingots, very hard. The NiMg3 sinks to the bottom so the Magnesium bubbles up through the iron to make the carbon nobules.
Billy, do you know what happens if you use too much NiMg in the ladle? I read somewhere it's bad but can't find it. Seems like it was just turned into a bad alloy. I don't think it was an explosion or anything.

 

Here's something interesting:

https://patents.google.com/patent/US3385696

Patent talks about how to make the dreaded NiMg.

Oh, and it's possible to buy the stuff in 1kg amounts, though the cost is high, and the shipping, likely higher!

 

The way we did it you could add all you wanted and would just end up with ductile instead of CGI. The liquid can only absorb so much and the rest doesn't go into solution and floats on top of the pool. You get a little more flaring when it gets hit but thats about it. Maybe if you had the puckets and put too many under the melt it could cause a big burp..pop...small explosion. Don't think it would be anything major but that is based off my experience which is fairly limited with ductile and CGI.