Process for generating a semi-solid slurry

Abstract

A method of making a metal part by semi-solid metal injection molding which includes combining a first solid metal portion and a second liquid metal portion in a first chamber of an injection molding machine to form a semi-solid metal slurry and injecting the semi-solid metal slurry into a mold cavity to form a molded metal part.

1 . A method of making a metal part by semi-solid metal injection molding comprising: 
 combining a first solid metal portion and a second liquid metal portion in a first chamber of an injection molding machine to form a semi-solid metal slurry; and    injecting the semi-solid metal slurry into a mold cavity to form a molded metal part.    
     
     
         2 . The method of  claim 1 , wherein: 
 the first chamber comprises a shot chamber; and    the semi-solid metal slurry is injected from the shot chamber into the mold cavity.    
     
     
         3 . The method of  claim 2 , wherein the first solid metal portion is provided into the shot chamber before the second liquid metal portion is provided into the shot chamber.  
     
     
         4 . The method of  claim 3 , further comprising: 
 providing a grain refining agent into the shot chamber before providing the second liquid metal portion into the shot chamber; or    providing the grain refining agent into the second liquid metal portion before providing the second liquid metal portion into the shot chamber.    
     
     
         5 . The method of  claim 4 , wherein: 
 a combined volume of the slurry comprising the grain refining agent, the first solid metal portion and the second liquid metal portion is substantially equal to a volume of the mold cavity; and    a latent heat of the second liquid metal portion is sufficient to bring a temperature of the combined volume into a semi solid state.    
     
     
         6 . The method of  claim 5 , wherein the metal comprises aluminum or an aluminum alloy.  
     
     
         7 . The method of  claim 6 , wherein the metal comprises a hypereutectic alloy.  
     
     
         8 . The method of  claim 7 , wherein the metal comprises a 390 alloy.  
     
     
         9 . The method of  claim 8 , wherein the temperature of the semi-solid metal slurry is between 560° C. and 590° C.  
     
     
         10 . The method of  claim 7 , wherein the grain refining agent comprises a phosphorus containing alloy or a phosphorous bearing salt.  
     
     
         11 . The method of  claim 10 , wherein the grain refining agent comprises an alloy containing copper and phosphorus, an alloy containing aluminum, copper and phosphorus or a phosphorous-bearing salt.  
     
     
         12 . The method of  claim 6 , wherein the metal comprises a hypoeutectic or a non-silicon bearing alloy.  
     
     
         13 . The method of  claim 12 , wherein the metal comprises an A356 alloy.  
     
     
         14 . The method of  claim 13 , wherein the temperature of the semi-solid metal slurry is between 575° C. and 585° C.  
     
     
         15 . The method of  claim 1 , wherein the first solid metal portion and the second liquid metal portion comprise the same metal or metal alloy.  
     
     
         16 . The method of  claim 1 , wherein the first solid metal portion comprises a solid grain refining agent which is adapted to refine grains of a second metal alloy and the second liquid metal portion comprises the second metal alloy.  
     
     
         17 . The method of  claim 13 , wherein the grain refining agent comprises an alloy containing titanium, or boron or combinations thereof.  
     
     
         18 . The method of  claim 5 , wherein the first solid metal portion comprises 5 to 30 volume percent of the combined volume of the semi-solid metal slurry in the shot chamber.  
     
     
         19 . The method of  claim 1 , further comprising: 
 removing a third solid metal portion of the molded metal part; and    providing the third solid metal portion into the first chamber of the injection molding machine during a subsequent step of forming a subsequent molded metal part.    
     
     
         20 . The method of  claim 19 , wherein the mold cavity includes a secondary cavity portion, the secondary cavity portion having a volume substantially equal to the third solid metal portion.  
     
     
         21 . The method of  claim 20 , wherein the secondary cavity portion has a surface area to volume ratio of at least 5:1.  
     
     
         22 . The method of  claim 21 , wherein the surface area to volume ratio is greater than 10:1.  
     
     
         23 . The method of  claim 21 , wherein the secondary cavity portion contains fin or spike shaped regions to form the third solid metal portion having fins or spikes.  
     
     
         24 . The method of  claim 20 , further comprising placing a grain refinement agent into the secondary cavity portion prior to injecting the semi-solid metal into the mold cavity, such that the grain refinement agent is entrapped in the third solid metal portion.  
     
     
         25 . The method of  claim 2 , wherein the shot chamber comprises a vertically oriented shot chamber having a horizontal width that is at least two times greater than a vertical depth of melt in the chamber.  
     
     
         26 . The method of  claim 25 , wherein: 
 the semi-solid slurry forms in the shot chamber with a generally globular or equiaxed primary phase microstructure without stirring the semi-solid slurry; and    the semi-solid slurry injected into a mold cavity by advancing a shot piston upwardly in the shot chamber.    
     
     
         27 . A molded metal part made by the method of  claim 1 .  
     
     
         28 . The part of  claim 19 , wherein the part comprises a first region that is richer in primary particles than a second region.  
     
     
         29 . A method of making a metal part by semi-solid metal injection molding, comprising: 
 providing a solid metal heat sink into a shot chamber of an injection molding machine:    providing liquid metal over the heat sink to form a semi-solid metal slurry; and    injecting the semi-solid metal slurry into a mold cavity to form a molded metal part.    
     
     
         30 . The method of  claim 29 , further comprising 
 providing a grain refining agent into shot chamber before providing the liquid metal into the shot chamber; or    providing liquid metal including a grain refining agent.    
     
     
         31 . The method of  claim 30 , wherein: 
 a combined volume of the slurry comprising the grain refining agent, the first solid metal portion and the second liquid metal portion is substantially equal to a volume of the mold cavity; and    a latent heat of the second liquid metal portion is sufficient to bring a temperature of the combined volume into a semi solid state.    
     
     
         32 . The method of  claim 31 , wherein: 
 the metal comprises a hypereutectic aluminum alloy;    the temperature of the semi-solid metal slurry is between 505° C. and 600° C.; and    the grain refining agent comprises a phosphorus containing alloy or a phosphorous bearing salt.    
     
     
         33 . The method of  claim 32 , wherein: 
 the metal comprises a 390 aluminum alloy;    the temperature of the semi-solid metal slurry is between 560° C. and 590° C.; and    the grain refining agent comprises an alloy containing copper and phosphorus, an alloy containing aluminum, copper and phosphorous or phosphorous-bearing salt.    
     
     
         34 . The method of  claim 31 , wherein: 
 the metal comprises a hypoeutectic or a non-silicon bearing aluminum alloy;    the temperature of the semi-solid metal slurry is between 560° C. and 600° C.; and    the grain refining agent comprises an alloy containing titanium, or boron or combinations thereof.    
     
     
         35 . The method of  claim 34 , wherein: 
 the metal comprises an A356 aluminum alloy;    the temperature of the semi-solid metal slurry is between 575° C. and 585° C.    
     
     
         36 . The method of  claim 31 , wherein the heat sink comprises 5 to 30 volume percent of the combined volume of the semi-solid slurry in the shot chamber.  
     
     
         37 . The method of  claim 36 , further comprising: 
 removing an appendage from the molded metal part; and    providing the appendage back into the shot chamber of the injection molding machine during a subsequent step of forming a subsequent molded metal part.    
     
     
         38 . The method of  claim 37 , wherein: 
 the mold cavity includes a secondary cavity portion, the secondary cavity portion having a volume substantially equal to the appendage;    the secondary cavity portion has a surface area to volume ratio of at least 5:1.    
     
     
         39 . The method of  claim 38 , further comprising placing a grain refinement agent into the secondary cavity portion prior to injecting the semi-solid metal into the mold cavity, such that the grain refinement agent is entrapped in the appendage.  
     
     
         40 . The method of  claim 29 , wherein: 
 the shot chamber comprises a vertically oriented shot chamber having a horizontal width that is at least two times greater than a vertical depth of melt in the shot chamber;    the semi-solid slurry forms in the shot chamber with a generally globular or equiaxed primary phase microstructure without stirring the semi-solid slurry; and    the semi-solid slurry is injected into a mold cavity by advancing a shot piston upwardly in the shot chamber.    
     
     
         41 . The method of  claim 29 , wherein the solid metal heat sink and the liquid metal comprise the same metal or metal alloy.  
     
     
         42 . The method of  claim 29 , wherein the solid metal heat sink comprises a solid grain refining agent which is adapted to refine grains of a second metal alloy and the liquid metal comprises the second metal alloy.  
     
     
         43 . A molded metal part made by the method of  claim 29 .  
     
     
         44 . A method of making a metal part by semi-solid metal injection molding, comprising: 
 providing a solid metal heat sink into a shot chamber of an injection molding machine, wherein the shot chamber comprises a vertically oriented shot chamber having a horizontal width that is at least two times greater than a vertical depth of melt in the chamber;    providing a grain refining agent into shot chamber;    providing liquid metal over the heat sink and the grain refining agent to form a semi-solid metal slurry, wherein the semi-solid slurry forms in the shot chamber with a generally globular or equiaxed primary phase microstructure without stirring the semi-solid slurry;    injecting the semi-solid metal slurry from the shot chamber into a mold cavity to form a molded metal part having an appendage;    removing the appendage from the molded metal part; and    providing the appendage back into the shot chamber of the injection molding machine as a heat sink during a subsequent step of forming a subsequent molded metal part.    
     
     
         45 . The method of  claim 44 , wherein: 
 a combined volume of the slurry comprising the grain refining agent, the first solid metal portion and the second liquid metal portion is substantially equal to a volume of the mold cavity; and    a latent heat of the second liquid metal portion is sufficient to bring a temperature of the combined volume into a semi solid state.    
     
     
         46 . The method of  claim 44 , wherein the metal comprises a hypereutectic alloy.  
     
     
         47 . The method of  claim 46 , wherein: 
 the temperature of the semi-solid metal slurry is between 505° C. and 600° C.; and    the grain refining agent comprises a phosphorus containing alloy or a phosphorous bearing salt.    
     
     
         48 . The method of  claim 47 , wherein: 
 the metal comprises a 390 aluminum alloy; and    the temperature of the semi-solid slurry is between 560° C. and 590° C.; and    the grain refining agent comprises a copper and phosphorus containing alloy.    
     
     
         49 . The method of  claim 44 , wherein the metal comprises a hypoeutectic or a non-silicon bearing alloy.  
     
     
         50 . The method of  claim 49 , wherein: 
 the temperature of the semi-solid metal slurry is between 560° C. and 600° C.; and    the grain refining agent comprises an alloy containing titanium, or boron or combinations thereof.    
     
     
         51 . The method of  claim 50 , wherein: 
 the metal comprises an A356 aluminum alloy;    the temperature of the semi-solid metal slurry is between 575° C. and 585° C.    
     
     
         52 . The method of  claim 45 , wherein the heat sink comprises 5 to 30 volume percent of the combined volume of the semi-solid slurry in the shot chamber.  
     
     
         53 . The method of  claim 52 , wherein: 
 the mold cavity includes a secondary cavity portion, the secondary cavity portion having a volume substantially equal to the appendage;    the secondary cavity portion has a surface area to volume ratio of at least 5:1.    
     
     
         54 . The method of  claim 44 , further comprising placing a grain refinement agent into the secondary cavity portion prior to injecting the semi-solid metal into the mold cavity, such that the grain refinement agent is entrapped in the appendage.  
     
     
         55 . The method of  claim 44 , wherein the solid metal heat sink and the liquid metal comprise the same metal or metal alloy.  
     
     
         56 . The method of  claim 55 , wherein the solid metal sink further comprises a grain refining agent which is adapted to refine grains of a second metal alloy and liquid metal comprises the second metal alloy.  
     
     
         57 . A molded metal part made by the method of  claim 44.