Superplastic aluminum alloy products and method of preparation

Claim 1

A method of preparing a superplastic aluminum alloy product, comprising (a) casting an alloy consisting essentially of 2-8% Ca, 1.5-15% Zn, up to 2% each of Mg, Si, Mn and Cu, up to 2% total (up to 1.0% max. each) of other elements, balance Al, for producing from a melt of the alloy a cast mass which includes, in an aluminum matrix, fine eutectic Ca-Zn-Al intermetallic rods formed from the melt in the casting operation; and (b) working the cast mass for breaking up the rods into particles having an average particle diameter of less than two microns such that the worked mass, when heated to a forming temperature between about 400° and 500° C., is superplastic.

Claim 2

A method of preparing a superplastic aluminum alloy product, comprising (a) casting an alloy consisting essentially of 2-8% Ca, 1.5-15% Zn, up to 2% each of Mg, Si, Mn and Cu, up to 2% total (up to 1.0% max. each) of other elements, balance Al, for producing from a melt of the alloy a cast mass which includes, in an aluminum matrix, fine eutectic Ca-Zn-Al intermetallic rods formed from the melt in the casting operation; and (b) working the cast mass for breaking up the rods into particles having an average particle diameter of less than two microns such that the worked mass, when heated to a forming temperature between about 400° and 500° C., is superplastic.

Claim 6

A method of preparing a superplastic aluminum alloy product, comprising (a) casting an alloy consisting essentially of 2-8% Ca, 1.5-15% Zn, up to 2% each of Mg, Si, Mn and Cu, up to 2% total (up to 1.0% max. each) of other elements, balance Al, by a continuous casting process, at a growth rate of at least 1 cm/minute at the solidification front, for producing from a melt of the alloy a cast mass which includes in an aluminum matrix, at least 10 volume percent fine eutectic Ca-Zn-Al intermetallic rods formed from the melt in the casting operation with an average diameter in the range of 0.05-1.50 microns and for suppressing the growth of coarse primary intermetallic particles such that the cast mass is essentially free of said coarse primary particles; and (b) working the cast mass for breaking up the rods into particles having an average particle diameter of less than two microns such that the worked mass, when heated to a forming temperature between about 400° C. and 500° C., has a tensile elongation of at least about 200% and a strain rate sensitivity index of at least about 0.3.

Claim 7

A method of preparing a superplastic aluminum alloy product, comprising (a) casting an alloy consisting essentially of 2-8% Ca, 1.5-15% Zn, up to 2% each of Mg, Si, Mn and Cu, up to 2% total (up to 1.0% max. each) of other elements, balance Al, by a continuous casting process, at a growth rate of at least 1 cm/minute at the solidification front, for producing from a melt of the alloy a cast mass which includes in an aluminum matrix, at least 10 volume percent fine eutectic Ca-Zn-Al intermetallic rods formed from the melt in the casting operation with an average diameter in the range of 0.05-1.50 microns and for suppressing the growth of coarse primary intermetallic particles such that the cast mass is essentially free of said coarse primary particles; and (b) working the cast mass for breaking up the rods into particles having an average particle diameter of less than two microns such that the worked mass, when heated to a forming temperature between about 400° C. and 500° C., has a tensile elongation of at least about 200% and a strain rate sensitivity index of at least about 0.3.

Claim 10

A method of producing an aluminum alloy ingot coprising casting an alloy consisting essentially of 2-8% Ca, 1.5-15% Zn, up to 2% each of Mg, Si, Mn and Cu, up to 2% total (up to 1.0% max. each) of other elements, balance Al, for producing from a melt of the alloy a cast mass which includes, in an aluminum matrix, at least 10 volume percent of eutectic Ca-Zn-Al intermetallic rods formed from the melt in the casting operation with an average diameter of 0.05-1.50 microns and breakable, by working of the cast mass, into particles having an average particle diameter of less than two microns, said cast mass being essentially free of coarse primary intermetallic particles.

Claim 11

A method of producing an aluminum alloy ingot coprising casting an alloy consisting essentially of 2-8% Ca, 1.5-15% Zn, up to 2% each of Mg, Si, Mn and Cu, up to 2% total (up to 1.0% max. each) of other elements, balance Al, for producing from a melt of the alloy a cast mass which includes, in an aluminum matrix, at least 10 volume percent of eutectic Ca-Zn-Al intermetallic rods formed from the melt in the casting operation with an average diameter of 0.05-1.50 microns and breakable, by working of the cast mass, into particles having an average particle diameter of less than two microns, said cast mass being essentially free of coarse primary intermetallic particles.