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melting/casting Aluminum Bronze is it fubar?


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I started some metal making for engraving and or other stuff
and the aluminum bronze is always incredibly dirty and difficult to manage, half of the metal clumps up into a porous black gunky mass that sticks to my crucible, every time.

however, this does not happen with my shibuichi+crucible, that one is nice and clean! no problems!

so am I crazy or doing something wrong or

is aluminum just an unholy disgusting metal for melting?
 

IMG_20211012_171319.jpg

IMG_20211012_171537.jpg

IMG_20211012_171546.jpg

 

And that's my shibuichi crucible

IMG_20211012_171349.jpg

Edited by J.Leon_Szesny
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18 minutes ago, J.Leon_Szesny said:

I started some metal making for engraving and or other stuff
and the aluminum bronze is always incredibly dirty and difficult to manage, half of the metal clumps up into a porous black gunky mass that sticks to my crucible, every time.

however, this does not happen with my shibuichi+crucible, that one is nice and clean! no problems!

so am I crazy or doing something wrong or

is aluminum just an unholy disgusting metal for melting?
 

IMG_20211012_171319.jpg

IMG_20211012_171537.jpg

IMG_20211012_171546.jpg

 

And that's my shibuichi crucible

IMG_20211012_171349.jpg

 

Did you prep the crucibles?    

 

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@DanM yea, I had it fluxed up but maybe not enough? Still doesn't explain the spongy mess that also resists melting...

Right?

Edited by J.Leon_Szesny
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56 minutes ago, J.Leon_Szesny said:

aluminum just an unholy disgusting metal for melting

 

Aluminum comes in a great number of alloys, some of which are not suitable for alloying with copper.  If your source metal is extruded and anodized, chances are it's not going to cast well.  If you're using scrap, make sure it was from a cast aluminum object like an engine block or something.

 

Looks like you're having oxygen issues?  Are you using a torch or a forge?  Regardless, listen to Dan, he's far more experienced than I am. B)

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I've made a few hundred (probably actually a few thousand) pounds of aluminum bronze commercially.  After reviewing the specs, sending out test bars for tensile testing and all that, I came to the conclusion that it is definitely not one that I ever want to play with in the home shop.  Way too finicky.  There are much easier to deal with options out there.  To get any good properties the chemistry has to be pretty tight (we ran a bunch of tests on the spectrometer), but the heat treat was pretty easy.  Gas was always an issue, but we had a few tricks to get our castings to come out.  Mainly ways to keep oxygen away.  

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I've been using aluminium wire and used to do it in a forge but recently got a Roxy torch set.

Still, forge or Roxy, same gunked up crucible.

Edited by J.Leon_Szesny
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I think I can confirm by now that aluminium is badbad stuff!

 

It seems to makes everything gunk up and that gunk prevents the metal from properly melting and flowing. 

 

Which is weird cuz aluminum melts so easily...

But as soon as it gets mixed somewhat with copper both metals...ugh

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Phase diagram of the bulk Al-Cu alloy.

Things get crazy in these alloys.  Little bit of copper in Al?  No problem.  Little bit of Al in Cu?  *CRAZINESS!*

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12 hours ago, Jerrod Miller said:

Phase diagram of the bulk Al-Cu alloy.

Things get crazy in these alloys.  Little bit of copper in Al?  No problem.  Little bit of Al in Cu?  *CRAZINESS!*

No idea how to read that but 

Yea.

I think I'll stick to Nordic gold, appearance wise that oughta work.

 

Also, this is what brass with aluminium bronze and phospherous bronze mixed looks like(the one on the left, the right is Nordic gold)

IMG_20211014_115034.jpg

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Yeah, I've had similar problems. Also with nordic gold (or real fake pirate gold as I also know it ;)), which also contains aluminium. Thanks for reminding me not to deal with this, and certainly not messing up my crucibles with it! If it casts, it looks nice. But it very easily turns into a sticky goo if you try to melt it. 

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5 hours ago, Jeroen Zuiderwijk said:

Yeah, I've had similar problems. Also with nordic gold (or real fake pirate gold as I also know it ;)), which also contains aluminium. Thanks for reminding me not to deal with this, and certainly not messing up my crucibles with it! If it casts, it looks nice. But it very easily turns into a sticky goo if you try to melt it. 

Nordic gold so far seems to be less problematic than trying to throw raw aluminium into a mix.

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6 hours ago, J.Leon_Szesny said:

No idea how to read

I would highly recommend learning all about phase diagrams in general (because they're fun; maybe that's just me), but especially if you are going to try creating your own alloys.  I wouldn't even think about building an alloy before consulting phase diagrams.  

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3 hours ago, Jerrod Miller said:

I would highly recommend learning all about phase diagrams in general (because they're fun; maybe that's just me), but especially if you are going to try creating your own alloys.  I wouldn't even think about building an alloy before consulting phase diagrams.  

hnng aight aight..
any info on finding some nice and palatable introduction to understanding this stuff?
(I am kinda...not..smart)

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I don't know of any that I am familiar with off the top of my head.  A quick search and I found this link from the very trustworthy ASM International (the fine folks that put the Heat Treater's Guide together).  I also found it funny that this video from Texas A&M started with the Cu-Al diagram (I just watched the first minute and last 2 minutes, where he came back to that diagram).  I think it may be a great starting place.  

Edited by Jerrod Miller
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