Deming Pan Try melting in an atmosphere of N2 or, if possible with appropriate safety considerations, H2. Store under nitrogen after synthesis.

Alan F Rawle Thank you for your answer. But pardon me, for some reason I am unable to use hydrogen gas in the laboratory, and the main problem is that I failed to remove the oxide film on the surface of magnesium at ambient condition that contains oxygen before I put the materials into the vacuum arc furnace.

Is there any way to remove the oxide on the surface of magnesium as much as possible and keep it from oxidation before I put the materials into the furnace?

Deming Pan MgO is a very difficult oxide to reduce (as it's more reactive than H2 as the Ellingham diagram will show. See: https://web.mit.edu/2.813/www/readings/Ellingham_diagrams.pdf attached). Indeed H2 cannot reduce it to the metal - such an atmosphere would be just to remove any other oxygen containing species. Only route I would try would be a plasma etching process in the appropriate atmosphere. In air the MgO film will form instantly, so air must be excluded. Other route would be to melt the Mg in the furnace and use some type of flux there to remove the MgO. This is potentially wasteful of your Mg.

Alan F Rawle Maybe I really need to try the methods you suggested. Thank you very much for your reply and the information you provided.

Deming Pan If you haven’t already seen this then the following paper could be useful: Article Synthesis and characterization of magnesium melting fluxes

Deming Pan One thing to note is that Mg will react vigorously with water if the oxide film isn't present. Indeed, even with the film, it'll slowly react as shown by putting some turnings in a beaker of water with a funnel above leading to a test tube. In about a week the test tube will be filled with H2. One can remove the film by amalgamating with Hg. In this way the Mg will then react vigorously with water. This suggests a route to pure Mg by amalgamation and then evaporation of the Hg under vacuum. This could be a dangerous process unless carefully controlled. Again air (and water) need to be carefully excluded from the system.

To remove oxidation from magnesium metal before melting it, you'll want to follow these steps:

Cleaning the Surface: Start by cleaning the surface of the magnesium. You can use a wire brush or sandpaper to remove any loose or flaky oxide layers.

Acid Bath: Prepare a dilute acid bath, such as a solution of hydrochloric acid (HCl) or acetic acid (vinegar). Immerse the magnesium piece in the acid bath. The acid will help dissolve the oxide layer.

Rinse Thoroughly: After soaking in the acid bath for a short period (a few minutes), remove the magnesium and rinse it thoroughly with water. This will wash away any remaining acid.

Drying: Ensure that the magnesium is completely dry before attempting to melt it. Use a clean cloth or paper towel to pat it dry.

Avoiding Contamination: Handle the magnesium with clean gloves or tweezers to avoid recontaminating it with oils or dirt from your skin.

Remember to exercise caution when working with acids, and wear appropriate safety gear such as gloves and eye protection. Additionally, always work in a well-ventilated area.

Keep in mind that magnesium can be highly reactive, so take appropriate safety measures, and consider seeking advice from a qualified professional if you are unsure about any part of the process.

Muhammad Fayaz The oxide layer is a few nm on Mg and forms instantly on exposure to air or water. All the steps you mention will need to take place in an inert or reducing atmosphere in the absence of water or oxygen containing molecules (e.g. alcohols).