# US 10,370,742 B2 · Hypereutectic aluminum-silicon cast alloys having unique microstructure

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- Number: US 10,370,742 B2
- Document ID: US10370742B2
- Status: Granted
- Kind: B2
- Application number: 15/263,859
- Filed: 2016-09-13
- Published: 2017-10-19
- Granted: 2019-08-06
- Earliest claimed: 2013-03-14
- Assignees: Brunswick Corporation
- Applicants: Brunswick Corporation
- Inventors: Raymond J. Donahue; Kevin R. Anderson; Terrance M. Cleary; Alexander K. Monroe
- Web page: https://patentgrep.com/patent/US10370742B2

## CPC

- C22C 21/02: with silicon as the next major constituent
- B22D 17/00: Pressure die casting or injection die casting, i.e. casting in which the metal is forced into a mould under high pressure
- B22D 21/007: {with low melting point, e.g. Al 659 degrees C, Mg 650 degrees C}
- C22C 21/04: Modified aluminium-silicon alloys
- C22C: ALLOYS (treatment of alloys C21D, C22F)
- B22D: CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES (shaping of plastics or substances in a plastic state B29C; metallurgical processing, selection of substances to be added to metal C21, C22)

## Abstract

A hypereutectic aluminum silicon high pressure die cast alloys is disclosed herein having 16% to 23% by weight silicon, 0.01% to 1.5% by weight iron, 0.01% to 0.6% by weight manganese, 0.01% to 1.3% by weight magnesium, 0.05% to 0.20% by weight strontium and the balance aluminum. The iron constituency may me modified to 0.01% to 0.7% by weight iron, or 0.01% to 0.2% by weight iron. The manganese constituency may be modified to 0.01% to 0.5% by weight manganese. The strontium constituency may be modified to 0.05% to 0.1% by weight strontium. The exhibits an elongation of at least 2%, an average ultimate tensile strength of greater than 250 MPa, and yield strength of greater than 200 MPa. The microstructure has a volume fraction of primary silicon at greater than 10% and a volume fraction of modified aluminum-silicon eutectic at 45% to 90%.

## Claims

### Claim 1

A hypereutectic high pressure die cast aluminum silicon alloy comprising: 16% to 23% by weight silicon; 0.01% to 1.5% by weight iron; 0.01% to 0.6% by weight manganese; 0.01% to 1.3% by weight magnesium; 0.05% to 0.20% by weight strontium and the balance aluminum; wherein the high pressure die cast alloy has a microstructure with a volume fraction of primary silicon of greater than 10%, and an elongation of at least 2%.

### Claim 2 (depends on 1)

The hypereutectic aluminum silicon alloy of claim 1, wherein the alloy has a microstructure with a volume fraction of primary silicon at 10% to 20%, a volume fraction of modified aluminum-silicon eutectic at 45% to 90%, and the balance of the microstructure primary aluminum.

### Claim 3 (depends on 2)

The hypereutectic aluminum silicon alloy of claim 2, wherein the volume fraction of primary silicon is surrounded by eutectic aluminum.

### Claim 4 (depends on 2)

The hypereutectic aluminum silicon alloy of claim 2, wherein the volume fraction of modified aluminum-silicon eutectic includes fibrous eutectic silicon.

### Claim 5 (depends on 2)

The hypereutectic aluminum silicon alloy of claim 2, wherein the microstructure primary aluminum is dendritic with an average dendritic arm spacing of less than 15 μm.

### Claim 6 (depends on 1)

The hypereutectic aluminum silicon alloy of claim 1, wherein the high pressure die cast aluminum silicon alloy comprises 0.01% to 0.7% by weight iron.

### Claim 7 (depends on 1)

The hypereutectic aluminum silicon alloy of claim 1, wherein the high pressure die cast aluminum silicon alloy comprises 0.01% to 0.2% by weight iron.

### Claim 8 (depends on 1)

The hypereutectic aluminum silicon alloy of claim 1, wherein the high pressure die cast aluminum silicon alloy comprises 0.01% to 0.5% by weight manganese.

### Claim 9 (depends on 1)

The hypereutectic aluminum silicon alloy of claim 1, wherein the high pressure die cast aluminum silicon alloy further comprises 0.01% to 4.5% by weight nickel.

### Claim 10 (depends on 1)

The hypereutectic aluminum silicon alloy of claim 1, wherein the high pressure die cast aluminum silicon alloy comprises 0.05% to 0.1% by weight strontium.

### Claim 11 (depends on 1)

The hypereutectic aluminum silicon alloy of claim 1, wherein the high pressure die cast aluminum silicon alloy has an average ultimate tensile strength of greater than 250 MPa.

### Claim 12 (depends on 1)

The hypereutectic aluminum silicon alloy of claim 1, wherein the high pressure die cast aluminum silicon alloy has a yield strength of greater than 200 MPa.

### Claim 13

A hypereutectic aluminum silicon alloy microstructure comprising: a volume fraction of primary silicon at 10% to 20%, a volume fraction of modified aluminum-silicon eutectic at 45% to 90%, and the balance of the microstructure primary aluminum.

### Claim 14 (depends on 13)

The hypereutectic aluminum silicon alloy microstructure of claim 13, wherein the volume fraction of primary silicon is surrounded by eutectic aluminum.

### Claim 15 (depends on 14)

The hypereutectic aluminum silicon alloy microstructure of claim 14, wherein the volume fracture of primary aluminum, including eutectic aluminum surrounding the primary aluminum is larger than the volume fraction of primary silicon.

### Claim 16 (depends on 13)

The hypereutectic aluminum silicon alloy microstructure of claim 13, wherein the volume fraction of primary silicon is surrounded by a modified eutectic containing a fibrous eutectic silicon phase.

### Claim 17 (depends on 13)

The hypereutectic aluminum silicon alloy microstructure of claim 13, wherein the microstructure primary aluminum is dendritic with an average dendritic arm spacing of less than 15 μm.

### Claim 18 (depends on 17)

The hypereutectic aluminum silicon alloy microstructure of claim 17 wherein the primary aluminum dendritic arm spacing is larger than the average primary silicon particle size.

### Claim 19 (depends on 13)

The hypereutectic aluminum silicon alloy microstructure of claim 13, wherein the alloy microstructure exhibits an elongation of at least 2%.

### Claim 20 (depends on 13)

The hypereutectic aluminum silicon alloy microstructure of claim 13, wherein the alloy microstructure exhibits an average ultimate tensile strength of greater than 250 MPa.

### Claim 21 (depends on 13)

The hypereutectic aluminum silicon alloy microstructure of claim 13, wherein the alloy microstructure exhibits yield strength of greater than 200 MPa.

### Claim 22 (depends on 13)

The hypereutectic aluminum silicon alloy microstructure of claim 13, wherein the average primary silicon particle size is less than 10 μm.

### Claim 23

A hypereutectic aluminum silicon alloy comprising 16-23% by weight silicon, 0.01 to 1.5% by weight iron, 0.20-5% by weight copper, 0.01 to 4.5% by weight nickel, 0.01 to 0.30% by weight manganese, 0.40-1.3% by weight magnesium, 0.05 to 0.10% by weight strontium, and the balance aluminum wherein the alloy when cast demonstrates an elongation of greater than 2%.