2020 Volume 61 Issue 9 Pages 1790-1797
We investigated the possibility of atomizing a molten magnesium (Mg) alloy by air instead of argon gas in order to manufacture the powder at a low cost. As a result, we obtained a powder from a molten Mg alloy containing yttrium (Y), calcium (Ca) or aluminum (Al) by air atomization without combustion. Each powder had an approximately 100-nm thick oxide film with condensed Y, Ca or Al, which can make the oxide film dense enough to isolate the molten Mg alloy droplet surface from air. In the case of Al, 6 mass%Al or more was required to prevent combustion. Al was also condensed in the matrix near the interface with the oxide film, which can reduce the Mg vapor pressure on the matrix surface under the oxide film. A high cooling rate of the droplet is also effective to prevent combustion. As air-atomized AZX912 powder has the same matrix structures as the argon-gas-atomized one, we expect that the sintered parts of the air-atomized Mg alloy powder can be obtained by breaking the oxide film during the forming and sintering process.
This Paper was Originally Published in Japanese in J. Jpn. Soc. Powder Powder Metallurgy 66 (2019) 485–492.
