Claims
- 1. A method for nodulizing silicon in Al—Si alloy castings having a silicon (Si) content in the range of 8.0-23.0%, which comprises:
a) forming a melt by heating a selected start Al—Si alloy mass to its alloy liquidus temperature; b) adding a master alloy mixture to the melt at a master alloy temperature of 150° C. above the start alloy liquidus temperature, said master alloy mixture comprising quantities of Ti, B, Zr and rare earth elements sufficient such that the Al—Si alloy casting comprises 0.02-0.30% Ti, 0.001-0.10% B, 0.02-0.10% Zr, and 0.03-0.3% rare earth elements by weight; c) forming a treated molten mass by degassing the melt with nitrogen; d) producing a casting by pouring and casting the treated molten mass; e) treating the casting further in solution by:
(1) heating the casting at a temperature of 500-530° C., and holding that temperature for a time sufficient to obtain a solid solution Al—Si alloy; and (2) quenching the solid solution alloy casting at high temperature in water; and f) aging the new Al—Si alloy casting by heating for a time sufficient to obtain desired alloy mechanical characteristics.
- 2. The method as recited in claim 1, wherein the added master alloy mixture comprises metal salts of Ti, B, Zr, and the rare earth elements.
- 3. The method as recited in claim 1, wherein the added master alloy mixture comprises: an Al—Ti alloy having 1-10% by weight titanium and 90-99% by weight aluminum; an Al—B alloy having 0.2-3.0% by weight boron and the balance being aluminum; an Al-RE alloy having 4.0-10% by weight rare earth elements and 90-96.0% by weight aluminum; and an Al—Zr alloy having 1.0-5.0% by weight zirconium and the balance being aluminum and incidental impurities.
- 4. The method as recited in claim 1, wherein the added master alloy mixture comprises: titanium alkalifluoride, alkali boron fluoride, zirconium alkalifluoride, rare earth chloride.
- 5. The method as recited in claim 1, further comprising stirring the master alloy mixture in the melt and holding for a period of time.
- 6. The method as recited in claim 1, wherein the casting heating is maintained for 6-8 hours.
- 7. The method as recited in claim 1, wherein the aging step is carried for 6-9 hours.
- 8. The method as recited in claim 1, wherein the aging step is carried out at a temperature of 130-230° C.
- 9. The method as recited in claim 1, wherein the overall weight of the master alloy is about 3% of the weight of the molten mass.
- 10. The method as recited in claim 1, wherein the start Al—Si alloy further comprises: Cu, Mg, Mn and Fe.
- 11. The method as recited in claim 1, wherein the start Al—Si alloy further comprises: 0.8-1.5% Cu, 0.6-1.0% Mg, <0.5% Mn, and <0.7% Fe by weight.
- 12. The method as recited in claim 1, wherein the master alloy mixture further comprises quantities of P sufficient such that the Al—Si alloy casting comprises 0.005-0.1% P.
- 13. The method as recited in claim 1, wherein the added master alloy mixture further comprises quantities of metal salts of P sufficient such that the Al—Si alloy casting comprises 0.005-0.1% P.
- 14. The method as recited in claim 1, wherein the added master alloy mixture further comprises quantities of phosphide sufficient such that the Al—Si alloy casting comprises 0.005-0.1% P.
- 15. The method as recited in claim 1, wherein the added master alloy mixture further comprises a Cu—P alloy having 5.0-8.0% by weight phosphorous and 92.0-95.0% by weight copper.
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation of allowed application Ser. No. 09/570,631, filed May 15, 2000.
Continuations (1)
|
Number |
Date |
Country |
Parent |
09570631 |
May 2000 |
US |
Child |
09854806 |
May 2001 |
US |