Howmet Corporation

Howmet Research Corporation

Gregory N Colvin

Stewart J Veeck

Donald E Larsen, Jr

William R Freeman

Robert F Johnson

Leonard L Ervin

Andrew L Matthews

Steven A Salter

A metal or alloy is melted in a vaccuum chamber disposed about an end of a shot sleeve. The opposite end of the shot sleeve is communicated to a die cavity between first and second dies which are disposed in ambient air atmosphere. The dies have one or more vacuum seals therebetween extending about the die cavity to isolate the die cavity from the ambient air atmosphere when the dies are closed. A vacuum thereby is provided in the die cavity through the shot sleeve when the vacuum chamber is evacuated despite the dies being disposed in ambient air atmosphere. The first and second dies are opened after the metal or alloy is die cast in the die cavity for ready removal of the cast component from the die cavity directly to the ambient air atmosphere and then to an optional quenchant medium proximate the dies.

High vacuum die casting

A method for die casting an amorphous metal or alloy using high vacuum die casting machine and die casting parameters effective to produce three dimensional net shape die cast components that retain at least 50 volume % or more amorphous phase in the die cast microstructure. The die cavity is evacuated to a vacuum level of less than 1000 microns through the shot sleeve, a superheated molten amorphous zirconium-copper-nickel-berylium alloy is introduced into the shot sleeve, the plunger is advanced at speeds in the range of 5 inches/second to 500 inches/second to force the molten metal or alloy into a sealed, evacuated die cavity where at least the outer surface or shell of the die cast component can solidify before opening of the dies to break the vacuum seal(s) and expose the cast component to ambient air atmosphere. The die component is removed from the opended dies and quenched in a quenchant medium, such as water, to produce a die cast microstructure including at least 50 volume % amorphous phase.

Vacuum die casting of amorphous alloys

A method of making a casting reinforced with a reinforcement insert, such as a fiber reinforced metal matrix composite insert or intermetallic insert therein, wherein a preformed fiber reinforced metal matrix composite reinforcement insert is clad or covered with a material that is effective to avoid the aforementioned adverse reactions between the insert/melt and any exposed insert fibers/matrix, the clad insert is suspended in the mold cavity, a melt is introduced into the mold cavity about the clad insert, and the melt is solidified about the clad insert to provide a casting of the solidified melt having the clad insert disposed therein to reinforce the casting.

Method of making composite castings using reinforcement insert cladding

A preformed fiber reinforced metal matrix composite reinforcement insert is clad or covered with a material that is effective to avoid the adverse reactions between the insert/melt and any exposed insert fibers/matrix. The clad insert is suspended in the mold cavity and a melt is introduced into the mold cavity about the clad insert. The melt is solidified about the clad insert to provide a casting of the solidified melt having the clad insert disposed therein to reinforce the casting.

Method and apparatus are provided for casting titanium-aluminum alloys including generally 10 weight % or more Al in a reusable metallic mold or die in a manner that retards or avoids build-up of a deleterious aluminum layer on the mold or die cavity surfaces that adversely affects surface quality of castings solidified therein.

Permanent mold or die casting of titanium-aluminum alloys

For a steel mold, one or more titanium melt inlet-forming members are provided for cooperating with the steel mold members to form an melt ingate that communicates to the mold cavity for supplying the melt thereto in a manner to avoid harmful iron contamination of the melt during casting. The mold body-to-mold cavity volume ratio is controlled between 10:1 to 0.5:1 to minimize casting surface defects and mold wear/damage.

Permanent mold for casting reactive melt

A method of making a composite casting wherein a casting mold is provided having a melt-receiving mold cavity and a preformed metallic or intermetallic insert located in a predetermined position in the mold cavity. A melt is introduced into the mold cavity about the insert and is solidified to provide a composite casting having one or more interfaces between the insert, or an insert positioning member, and cast/solidified metal about the insert. The interface is exposed on or communicates with an exterior surface of the composite casting. After separation from the mold, the composite casting is subjected to a sealing operation to gas-tight seal the interface(s) at the exterior casting surface. For example, the interface can be sealed by providing fused material at the interface. After the interface(s) is (are) sealed, the composite casting is subjected to elevated temperature and isostatic gas pressure conditions effective to produce a sound, void-free, contamination-free metallurgical bond between the insert and the cast melt thereabout. The previously sealed interface(s) prevent the pressurizing gas from entering and migrating between the insert and the cast melt so as to enable formation of the sound, void-free, contamination-free bond.

Composite casting method

Titanium based and nickel based castings are made by casting a suitable melt having a relatively low melt superheat into a mold cavity defined by one or more low carbon steel or titanium mold members where the melt solidifies to form the desired casting. The melt super-heat is limited so as not to exceed about 150.degree. F. above the liquidus temperature of the particular melt being cast. For a steel mold, one or more titanium melt inlet-forming members are provided for cooperating with the steel mold members to form an melt ingate that communicates to the mold cavity for supplying the melt thereto in a manner to avoid harmful iron contamination of the melt during casting. The mold body-to-mold cavity volume ratio is controlled between 10:1 to 0.5:1 to minimize casting surface defects and mold wear/damage.

Permanent mold casting of reactive melt

A method of making a composite casting wherein a casting mold is provided for receiving a melt and a preformed metallic or intermetallic insert is positioned in the mold cavity. The preformed insert includes a working portion for incorporation in the casting and gas seal-forming means located at a region of the insert at least outboard of the insert portion. A melt is introduced into the mold about the insert and is then solidified to provide a composite casting having the insert working portion disposed in the solidified melt and as-cast gas seal regions located outboard of the insert working portion in the casting. The casting is then subjected to elevated temperature and isostatic gas pressure conditions wherein the as-cast gas seal regions are effective to inhibit gas penetration between the insert working portion and the solidified melt therearound so as to permit formation of a sound, void-free metallurgical bond therebetween. The hot isostatically pressed casting can then be trimmed to remove, if desired, those outboard portions containing the gas seal regions, leaving a finished casting having the insert working portion metallurgically bonded therein in a sound, void-free manner.

Method of making a composite casting

A casting mold includes a melt-receiving mold cavity having a preformed metallic or intermetallic insert suspended therein by one or more first elongated, slender suspension members fixed at one end to the insert and at another end to the mold to locate the insert in a first direction in the mold and by one or more second elongated, slender suspension members fixed at one end to the insert and abutting the mold at another end to locate the insert in a second direction in the mold. A melt of metallic or intermetallic material is introduced into the mold cavity about the suspended insert and the suspension members and is solidified to form a composite casting. The casting is subjected to elevated temperature/elevated isostatic gas pressure conditions wherein the interface between the suspension members and the cast melt is effective to inhibit gas penetration between the insert and cast melt, thereby allowing a sound, void-free, contamination-free metallurgical bond to be produced between the insert and the cast melt.

A casting mold includes a melt-receiving mold cavity having a preformed metallic or intermetallic insert suspended therein by at least one elongated, slender suspension member fixed at one end to the insert and at another end to the mold. A melt of metallic or intermetallic material is introduced into the mold cavity about the suspended insert and the suspension member and is solidified to form a composite casting The casting is subjected to elevated temperature/elevated isostatic gas pressure conditions wherein the interface between the suspension member and the cast melt is effective to inhibit gas penetration between the insert and cast melt, thereby allowing a sound, void-free, contamination-free metallurgical bond to be produced between the insert and the cast melt.

Aluminum-lithium alloy and method of investment casting an aluminum-lithium alloy including the steps of providing an aluminum-lithium alloy melt having a composition consisting essentially of about 2.0 to about 2.8 w/o lithium, about 1.2 to about 1.8 w/o copper provided that the combined lithium and copper content does not exceed 4.0 w/o, about 0.8 to about 1.0 w/o magnesium, the balance essentially aluminum, adding an effective amount of a grain refining agent to the aluminum-lithium alloy melt investment casting the melt, solution heat treating the aluminum-lithium alloy investment casting for up to 30 hours at continuously increasing temperatures to within approximately 30.degree. to 40.degree. F. of the solidus temperature of said aluminum-lithium alloy, and aging the aluminum-lithium alloy investment casting at a temperature and for a time sufficient to optimize the .delta.' precipitate size.

Growing community of inventors

Muskegon, MI, United States of America

Gregory N Colvin