Semi-solid metal casting process of hypereutectic aluminum alloys
View Patent ↗A method for the refining of primary silicon in hypereutectic alloys by mixing at least two hypereutectic alloys into a solid/semi-solid hypereutectic slurry is described. The method provides control of the morphology, size, and distribution of primary Si in a hypereutectic Al—Si casting by mixing a hypereutectic Al—Si liquid with solid hypereutectic Al—Si particles. The invention enables SSM processing of hypereutectic Al—Si alloys.
1. A method for semi-solid metal casting, comprising:
providing a first aluminum-silicon hypereutectic alloy and a second aluminum-silicon hypereutectic alloy;
heating the first alloy to a liquid state;
combining the first alloy and the second alloy to form a semi-solid metal;
increasing nucleation events of primary Silicon particles in the semi-solid metal by rapidly cooling the semi-solid metal by combining the first and second alloys at different temperatures and by decreasing the time the semi-solid metal remains in the semi-solid state before casting; and
casting the semi-solid metal in a cast machine.
2. The method of claim 1 , wherein the primary Silicon particles have an average diameter of between about 20 microns to about 50 microns.
3. The method of claim 2 , wherein the primary Silicon particles have an average diameter of less than about 40 microns.
4. The method claim 1 , wherein the first and second aluminum-silicon hypereutectic alloys are of the same composition.
5. The method of claim 1 , further comprising:
providing a third aluminum-silicon hypereutectic alloy; and
combining the third alloy with the first and second alloys.
6. The method of claim 1 , wherein the second alloy is at room temperature before being combined with the first alloy.
7. The method of claim 1 , further comprising heating the second alloy to a liquid state.
8. The method of claim 7 , wherein the first alloy is heated to a higher temperature than the second alloy.
9. The method of claim 1 , wherein the first alloy is heated to a temperature of about 600° C. to about 850° C.
10. The method of claim 9 , wherein the first alloy is heated to a temperature of about 630° C. to about 800° C.
11. The method of claim 1 , wherein the first alloy is heated to a temperature of about 760° C.
12. The method of claim 7 , wherein the second alloy is heated to a temperature from about 22° C. to about 640° C.
13. The method of claim 1 , wherein the first and second alloys are a 390 alloy.
14. The method of claim 7 , wherein the second alloy is heated to a temperature of about 600° C. to about 850° C.
15. The method of claim 14 , wherein the second alloy is heated to a temperature of about 630° C. to about 800° C.
16. The method of claim 7 , wherein the second alloy is heated to a temperature of about 760° C.