Microstructures and Mechanical Responses of Powder Metallurgy Noncombustive Magnesium Extruded Alloy by Rapid Solidification Process in Mass Production

Report No. ARL-CR-647
Authors: Katsuyoshi Kondoh, EL-Sayed Ayman Hamada, Hisashi Imai, and Junko Umeda
Date/Pages: May 2010; 26 pages
Abstract: Spinning water atomization process (SWAP), one of the rapid solidification processes, promised to produce coarse noncombustible magnesium alloy powder 1-4 mm long and have fine ±-Mg grains and Al2Ca intermetallic compounds. SWAP had economical and safe benefits in producing coarse Mg alloy powders with very fine microstructures in the mass production process due to its extreme high solidification rate compared to the conventional atomization process. AMX602 (Mg-6%Al-0.5%Mn-2%Ca) powders were compacted at room temperature. Their green compacts, with a relative density of about 85%, were heated at 573-673 K for 300 s in Ar gas atmosphere and immediately consolidated by hot extrusion. Microstructure observation and evaluation of mechanical properties of the extruded AMX602 alloys were carried out. The uniform and fine microstructures, with grains <0.45-0.8 µm via dynamic recrystallization during hot extrusion, were observed and much smaller in comparison to the extruded AMX602 alloy fabricated from cast ingot. The extremely fine intermetallic compounds, 200-500 nm in diameter, were uniformly distributed in the matrix of powder metallurgy extruded alloys. These microstructures caused excellent mechanical properties of the wrought alloys. For example, in the case of AMX602 alloys extruded at 573 K, tensile strength of 447 MPa, yield stress of 425 MPa, and 9.6% elongation were obtained.
Distribution: Approved for public release
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Last Update / Reviewed: May 1, 2010