# US 5,701,942 A · Semi-solid metal processing method and a process for casting alloy billets suitable for that processing method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,701,942 A - Document ID: US5701942A - Status: Granted - Kind: A - Application number: 08/683,023 - Filed: 1996-07-15 - Granted: 1997-12-30 - Earliest claimed: 1994-09-09 - Assignees: Ube Industries, Ltd. - Inventors: Mitsuru Adachi; Hiroto Sasaki; Satoru Sato - Web page: https://patentgrep.com/patent/US5701942A ## CPC - B22D 23/00: Casting processes not provided for in groups B22D1/00 - B22D21/00 (making metallic powder by casting B22F9/08; alumino-thermic welding B23K23/00; remelting metals C22B9/16) - C22C 1/12: by processing in a semi-solid state, e.g. holding the alloy in the solid-liquid phase - Y10S 164/90: Rheo-casting - 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) - C22C: ALLOYS (treatment of alloys C21D, C22F) - Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS ## Abstract A magnesium or aluminum alloy melt having a composition within maximum solubility limits is poured into a mold at a temperature exceeding the alloy liquidus line, but not higher by more than 30.degree. C., the melt is cooled at a rate of at least 1.0.degree. C./sec to form a billet, the billet is heated at a rate of at least 0.5.degree. C./min in a range bound by the alloy solubility line and the alloy solidus line and further heated to a temperature above the alloy solidus line and is maintained at that temperature for 5 to 60 minutes, thereby spheroidizing primary crystals thereof, the billet is then further heated to a temperature below the alloy liquidus line and the semi-solid billet is shaped under pressure. Alternatively, a hypo-eutectic aluminum alloy melt having a composition at or above maximum solubility limits is poured into a billet-forming mold at a temperature exceeding the alloy liquidus line, but not higher by more than 30.degree. C. and the melt is cooled at a rate of at least 1.0.degree. C./sec to form a billet, the billet is then heated to a temperature above the alloy eutectic point, the holding time and temperature are selected such that the liquid-phase content of the billet is adjusted to 20% to 80% and primary crystals thereof are spheroidized and, the semi-solid billet having the adjusted liquid-phase content is shaped under pressure. ## Claims ### Claim 1 A method of processing semi-solid metals comprising the steps of: (a) casting a melt of a magnesium alloy or an aluminum alloy having a composition within maximum solubility limits into a billet-forming mold, the melt being at a temperature as it is cast into said billet-forming mold which exceeds a liquidus line temperature of the alloy, but is not higher by more than 30.degree. C. of the liquidus line temperature; (b) cooling said melt to solidify said alloy within said billet-forming mold at a cooling rate of at least 1.0.degree. C./sec in a solidification zone to form a billet; (c) heating said billet within said billet-forming mold from a solubility line temperature to a solidus line temperature of the alloy at a rate of at least 0.5.degree. C./min; (d) further heating the billet from step (c) to a temperature exceeding the solidus line temperature of the alloy; (e) maintaining the billet from step (d) at the temperature in step (d) for 5-60 minutes, thereby spheroidizing primary crystals thereof; (f) further heating said billet from step (e) to a molding temperature below the liquidus line temperature of the alloy to form a semi-solid billet; (g) feeding the semi-solid billet into a shaping mold; and (h) forming the billet into a shape under pressure. ### Claim 2 A method of processing semi-solid metals comprising the steps of: (a) casting a melt of a hypo-eutectic aluminum alloy having a composition at or above maximum solubility limits into a billet-forming mold, the melt being at a temperature as it is cast into said mold which exceeds the liquidus line temperature of the alloy, but is not higher by more than 30.degree. C. of the liquidus line temperature; (b) cooling said melt to solidify said alloy within said billet-forming mold at a cooling rate of at least 1.0.degree. C./sec in a solidification zone so as to form a billet; (c) heating said billet to a temperature above the eutectic point of said alloy; (d) selecting a holding time and a temperature such that the billet has a liquid-phase content of between 20% and 80% and that primary crystals thereof are spheroidized, to form a semi-solid billet; (e) supplying the semi-solid billet from step (d) to a shaping mold; and (f) forming the billet from step (e) into a shape under pressure. ### Claim 3 (depends on 1) A method according to claim 1 wherein the alloy is a magnesium alloy which contains 0.005-0.1% Sr, a magnesium alloy which contains 0.05-0.3% Ca, or a magnesium alloy which contains 0.01-1.5% Si and 0.005-0.1% Sr. ### Claim 4 (depends on 1) A method according to claim 1 wherein the alloy is an aluminum alloy which contains 0.001-0.01% B and 0.005-0.30% Ti. ### Claim 5 (depends on 2) A method according to claim 2 wherein the aluminum alloy is one which contains 0.001-0.01% B and 0.005-0.30% Ti. ### Claim 6 (depends on 2) A method according to claim 2 wherein the aluminum alloy is one which contains 0.001-0.01% B, 0.005-0.30% Ti and 4-6% Si. ### Claim 7 (depends on 1, 2, 3, 4, 5, 6) A method according to any one of claims 1-6 wherein when the melt is cast into the billet-forming mold small vibrations are applied to said billet-forming mold in a direction generally perpendicular to a direction in which the melt is cast. ### Claim 8 (depends on 1) A method according to claim 1 wherein the cooling rate in the solidification zone is 5.degree. to 10.degree. C./second; and the billet is heated from the solubility line temperature to the solidus line temperature at a heating rate of 50.degree. to 100.degree. C./minute. ### Claim 9 (depends on 1) A method according to claim 1 wherein the alloy is an aluminum alloy which contains 4 to 6% Si and optionally contains at least one of Ti and B. ### Claim 10 (depends on 1) A method according to claim 1 wherein the alloy is a magnesium alloy which optionally contains at least one of Ca, Si and Sr. ### Claim 11 (depends on 1) A method according to claim 1 wherein the alloy is a magnesium alloy which contains 0.01 to 1.5% Si and 0.005 to 0.1% Sr. ### Claim 12 (depends on 2) A method according to claim 2 wherein the liquid-phase content of the billet is 30% to 70%. ### Claim 13 A process of casting an alloy billet suitable for a semi-solid metal processing method comprising the steps of: (a) holding a melt of an alloy selected from the group consisting of a magnesium alloy and an aluminum alloy at a temperature exceeding the liquidus line of the alloy, but not higher by more than 30.degree. C.; and (b) casting the melt in a billet-forming mold and cooling at a rate of at least 1.0.degree. C./sec over a solidification zone to form a billet of a structure comprising fine, equiaxed crystal grains. ### Claim 14 (depends on 13) A process according to claim 13 wherein the alloy is a magnesium alloy which contains 5-10% Al, 0.1-3.5% Zn and 0.1-0.6% Mn. ### Claim 15 (depends on 13) A process according to claim 13 wherein the alloy is a magnesium alloy which contains 5-12% Al and 0.1-0.6% Mn. ### Claim 16 (depends on 13) A process according to claim 13 wherein the alloy is an aluminum alloy which contains 0.001-0.01% B and 0.005-0.30% Ti. ### Claim 17 (depends on 13) A process according to claim 13 wherein the alloy is an aluminum alloy which contains 0.001-0.01% B, 0.005-0.30% Ti and 4-6% Si. ### Claim 18 (depends on 13, 14, 15, 16, 17) A process according to any one of claims 13-17 wherein when the melt is cast, small vibrations are applied to said billet-forming mold in a direction generally perpendicular to a direction in which the melt is cast. ### Claim 19 A method of processing semi-solid metals comprising the steps of: (a) casting a melt of (i) a magnesium alloy containing 0.005 to 1% Sr or 0.05 to 0.3% Ca or 0.01 to 1.5% Si and 0.005 to 1% Sr or (ii) an aluminum alloy containing 0.001 to 0.01% B and 0.005 to 0.30% Ti or 0.001 to 0.1% B, 0.005 to 0.30% Ti and 4 to 6% Si, and having a composition within maximum solubility limits, into a billet-forming mold, the melt being at a temperature as it is cast into said billet-forming mold which exceeds the liquidus line temperature of the alloy, but is not higher by more than 30.degree. C. of the liquidus line temperature; (b) cooling said melt to solidify said alloy within said billet-forming mold at a cooling rate of at least 1.0.degree. C./sec in a solidification zone to form a billet; (c) heating said billet within said billet-forming mold from the solubility line temperature to the solidus line temperature of the alloy at a rate of at least 0.5.degree. C./minute; (d) further heating the billet from step (c) to a temperature exceeding the solidus line temperature of the alloy; (e) maintaining the billet from step (d) at the temperature in step (d) for 5 to 60 minutes, thereby spheroidizing primary crystals thereof; (f) further heating said billet from step (e) to a molding temperature below the liquidus line temperature of the alloy to form a semi-solid billet; (g) feeding the semi-solid billet from step (f) into a shaping mold; and (h) forming the billet into a shape under pressure.