Hi, does anyone have a tip or technique to share for arc-melting Fe and Mn together? Our Mn chunks are not cooperating and seem to partially vaporize early on, drifting away from the crucible.
I would make/buy FeMn master alloy and then arc melt it with Fe for desired composition.
Why not induction melting? You have better control of temperature which may help to reduce evaporation.
In the arc melter, I would try to put the Mn at the bottom to avoid strong overheating before the Fe even becomes liquid.
Typical occurrence with Mn. It tends to vaporize rather swiftly. On average 5 wt.% loss. At my workplace one guy first premelted (levitation melting) Mn to obtain ear drops like chunks with desired mass. Then we used this for arc or induction melting with no Mn loss. This works perfect!
Due of manganese's instability, arc-melting Fe and Mn together might be difficult. Instead of pure Mn chunks, consider utilizing a FeMn master alloy. During arc melting, master alloys are often more stable and easier to handle. Place the Mn material near the bottom of the crucible when using arc melting. This can assist prevent quick vaporization by shielding it from the direct heat of the arc. Consider levitation to melt Mn into bits if possible. Because there is no contact with the crucible during the melting process, Mn loss is minimized. Mn loss can occur during arc melting due to fast heating of small metallic particles in crushed briquettes. Consider dealing with solid pieces of Mn rather than fine-grain powders to reduce losses.
1. E. Yüzüak pointed out that Mn is unstable during the melting process. To prevent significant evaporation of Mn due to its low melting point, slow heating must be employed to prepare Fe-Mn alloys.
2. If Mn is in powder form, it is recommended to compress it into pellets or other solid forms before melting to reduce weight loss.
3. To prevent any significant loss of Mn in the sample system, it is recommended to use an excess of 3% Mn.
Dear Marie-Agathe Charpagne
Hi,
I had similar issues with drifting materials during the arc melting. We noticed that it is mainly related to the significant thermal shock by the arc. Some brittle materials like Mn chunk cannot endure such a high level of thermal stresses and immediately break and drift away under the arc. As a practical simple solution, we put such materials at the bottom and put other materials on top of them. If you use this technique, you can put the Mn chunks under Fe particles. Hence, Mn does not experience the initial direct shock by the arc, and Fe can melt and immediately embrace Mn chunks. By keeping the arc and maybe remelting, the Mn particles will be dissolved entirely. This procedure might help to prevent vaporizing too. Since, when you put Mn on the bottom, it will be cooled by the copper crucible and therefore it won't reach high temperatures. By such a simple process we could solve our similar problem with mixing aluminum and refractory elements like Ta and Mo (the vapor point of Al is significantly lower than the melting point of Ta and Mo).
Due to the low density of Mn pellets, your Mn may have a higher volume than the Fe particles (depending on your alloy composition). Therefore, you may need to add the Mn in two or more steps.
I also recommend that cut your Fe particles into smaller bulks in order to cover the underneath Mn pellets more effectively.
I hope these points will be helpful in your experiments.
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