Superplastically formed product from rolled magnesium base metal alloy sheet
Magnesium base metal alloy sheet is produced by rolling the rolling stock extruded or forged from a billet at a temperature ranging from 200.degree. C. to 300.degree. C. The billet is consolidated from rapidly solidified magnesium based alloy powder that consists essentially of the formula Mg.sub.bal Al.sub.a Zn.sub.b X.sub.c, wherein X is at least one element selected from the group consisting of manganese, cerium, neodymium, praseodymium, and yttrium, "a" ranges from about 0 to 15 atom percent, "b" ranges from about 0 to 4 atom percent, "c" ranges from about 0.2 to 3 atom percent, the balance being magnesium and incidental impurities, with the proviso that the sum of aluminum and zinc present ranges from about 2 to 15 atom percent. The alloy has a uniform microstructure comprised of fine grain size ranging from 0.2-1.0 .mu.m together with precipitates of magnesium and aluminum containing intermetallic phases of a size less than 0.1 .mu.m. The sheets have a good combination of mechanical strength and ductility and are suitable for military, space, aerospace and automotive application. The sheets can be superplastically formed at temperatures ranging from 275.degree. C. to 300.degree. C. and at strain rates ranging from 10.sup.-1 to 10.sup.-2. The condition which maximizes superplastic ductility is a temperature of 300.degree. C. and a strain rate of 0.1/s. An elongation of 436%, combined with uniform deformation within the gage length, allows fabrication of complex shapes.
Allied-Signal Inc.
C C
C22F C22C
inventional inventional
Chin-Fong Santosh K.
Chang Das