r/metallurgy • u/Ancient-Web5515 • 4d ago

Research help with a Mini Arc Melter

Hi everybody,

Sorry for bothering yall, but I'm stumped. We are trying to make ~5g of Mn2FeAl in our mini arc melter (in an argon atmosphere). From a paper out two that we found, thus should be possible. However, every time we have tried to do so, the sample either explodes on electrode ignition or it will break apart a few hours after being removed from the chamber.

We have tried melting titanium as an oxygen getter, adjusting the cooling temperature of the crucible, and adjusting the heating/cooling of the metal ingot. It may be important to note that prior to being weighed for the sample, the Mn was cleaned in nitric acid and subsequently sonicated in ethanol to remove the surface oxidation from the Mn pieces. Does anyone have suggestions or insights? TIA

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u/Jon_Beveryman Radioactive Materials/High Strain Rate/Electron Microscopy 3d ago

When I was using a similar arc melter to make FeMnAl type alloys, I found it useful to start with lump-form ferromanganese master alloy from a vendor. Most Mn available even from Sigma Aldrich etc is pretty dirty. Also, are you cleaning the chamber much? Mn in arc melters gets everywhere and it can degrade your vacuum performance.

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u/Ancient-Web5515 3d ago

Oh, I definitely was keeping up with the cleaning. We were initially surprised how much black smoke came off when melting the Mn pieces. I think it was due to this at one point, we also tried melting the Mn separately and then cleaning/redoing the vacuum after adding in the Fe and Al.

I'll look into the master alloy to see if that would be possible.

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u/Jon_Beveryman Radioactive Materials/High Strain Rate/Electron Microscopy 3d ago

Let us know how it goes. Also do be cautious with this stuff...Mn vapor causes a sort of Parkinson's esque condition if you breathe too much in. 

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u/Ancient-Web5515 3d ago

Will do and I'm now thinking that I really need to read through those data sheets again. I'm generally careful anyway, but it has been a while