Rapid Solidification Processing of Magnesium Alloys.

Abstract
This report comprises the second year of a two year program on a Rapid Solidification, extrusion processing and mechanical property measurement of Magnesium alloys. During the second year, samples were cast using a controlled atmosphere (He gas), and vertical wheel melt-spinning apparatus constructed at MIT. Casting conditions were thus perfected, to obtain larger quantities of ribbons of consistent quality. Extrusion procedures were investigated on rapidly solidified magnesium alloys. A gradual lowering of the extrusion temperature from 470 C to 210 C yielded improved mechanical properties on alloys ZK60, EZ33, and Mg-5.3%Zn. Optimal conditions were: a reduction in area ratio of about 1/30, and an extrusion temperature of about 200-250 C. Results on alloy ZK60, extruded under these conditions, displayed interesting mechanical properties, and made it comparable in specific properties to R.S.P. aluminum alloys. Tensile properties in the as extruded condition were: U.S. 53.0 ksi, and U.T.S. 56.3 ksi. The ductility in particular was significantly higher than that of wrought ZK60 alloy: 19.6% (typical mechanical properties of the conventional extruded material are: Y.S. 41 ksi, U.T.S. 51 ksi, elongation, 11%). Originator furnished keywords include: Rapid soldification, Processing, Extrusion, Mechanical properties, Magnesium alloys, Power metallurgy.

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