US 5,118,026 A · Method for making titanium aluminide metallic sandwich structures

Abstract

A method for fabricating of intermetallic titanium aluminide sandwich structures in which blanks of titanium aluminide are bonded to one another, under vacuum in a retort, at selected areas to form a pack, and then, upon removal of the retort, expanded superplastically to form a desired sandwich structure. Bonding of the various preselected areas of the metal blanks is accomplished using elevated temperature gas diffusion bonding techniques. The invention contemplates a first thermal cycle during which the pack is diffusion bonded in an evacuated retort at one temperature within a predetermined range of temperatures, and a second thermal cycle during which subsequent superplastic forming of the pack of bonded blanks, with the retort removed, is carried out. Optionally, during the first thermal cycle, a step of superplastic preforming may be carried out whereby the pack is preformed against arcuate or other shaped forming members.

Claims20

Dependent claims

A method for forming metallic sandwich structures using titanium aluminide materials, comprising:

forming a stack of sheet metal blanks of said titanium aluminide materials on which stop-off materials have been applied to preselected regions of one or more of said sheet metal blanks,
sealing said stack within a retort,
evacuating said retort to provide a contamination-free, pressurized environment in said retort,
diffusion bonding selected areas of said stack at a first diffusion bonding temperature in said contamination-free environment,
removing said retort,
heating said diffusion bonded stack to a second superplastic forming temperature, and
applying expanding pressure to the interior of said stack at said second temperature to superplastically form a desired sandwich structure.

4 more elements

Apparatus for diffusion bonding selected regions of a stack of titanium aluminide sheets, comprising:

a first tool and a second tool having respective shaping surfaces,
means for containing said stack of sheets in a contamination-free environment, said containing means including on one exterior surface thereof a first sealing frame means adapted for sealing engagement with said first tool to define therewith a first volume,
means for moving said first and second tools relative to one another so that as said second tool supports said containing means adjacent said second tool shaping surface, said first tool sealingly engages with said first sealing frame means to define therewith and with said one exterior surface of said containing means a first chamber,
means for heating said first chamber and the elements defining said first chamber to a first temperature range within which diffusion bonding can take place,
gas delivery means for delivering gas under pressure to said first chamber whereby said gas in said first chamber presses uniformly against said containing means exterior surface with a force sufficient to cause diffusion bonding between said selected regions of said sheets of said stack.

2 more elements

Dependencies are inferred from the claim text.

Method for making titanium aluminide metallic sandwich structures

Life of this patent

Method for making titanium aluminide metallic sandwich structures

Life of this patent

Abstract

Claims20