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US3189442A - Magnesium-lithium-yttrium alloys - Google Patents

Magnesium-lithium-yttrium alloys Download PDF

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Publication number
US3189442A
US3189442A US283643A US28364363A US3189442A US 3189442 A US3189442 A US 3189442A US 283643 A US283643 A US 283643A US 28364363 A US28364363 A US 28364363A US 3189442 A US3189442 A US 3189442A
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magnesium
lithium
alloy
yttrium
percent
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US283643A
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Paul D Frost
Thomas G Byrer
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    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C23/00Alloys based on magnesium

Definitions

  • This invention relates to magnesium base alloys and more particularly to magnesium base alloys containing lithium and yttrium. Further, it concerns the beta phase of magnesium-lithium alloys employing yttrium.
  • magnesium base alloys are among the lightest of the structural alloys, they have not met with wide acceptance in applications where stressed parts are exposed to elevated temperatures.
  • Previous work has been done with magnesium-lithium alloys in an effort to increase hardness of the alloy at elevated temperatures without loss of the desirable properties such as lightness and ductility. These desired results are accomplished in this invention wherein the magnesium-lithium alloy is combined with yttrium to form an alloy with good stability and hardness at elevated temperatures.
  • the objects of this invention are accomplished by alloying magnesium and lithium in the ratio by weight of 7.5 magnesium to l lithium, and adding amounts of yttrium not to exceed 6 percent of the total weight of the alloy.
  • the ratio of 7.5 to 1 is necessary to insure the formation of the beta phase of the alloy wherein the lithium content cannot exceed 12 percent of the total weight of the alloy.
  • the order of addition of the metals to the magnesium is immaterial.
  • the magnesium and lithium may be melted together and the yttrium added or the yttrium may be added to the molten magnesium prior to the addition of the lithium.
  • 10 to 12 percent by weight lithium and 4 to 6 percent by weight yttrium are alloyed with magnesium to make a 100 percent alloy.
  • the magnesium and lithium are melted in an open top crucible with a flux protective cover.
  • An argon mantle can be used instead of the flux protective cover. Any suitable flux known in the art can be used in this operation.
  • the crucible is equipped with a stirring rod having a one inch flat disk fastened to the end. The yttrium is puddled into the solution using this stirring rod to insure complete stirring of the melt and better control over the addition of the yttrium.
  • the melt After alloying has been effected the melt is allowed to remain undisturbed for a time to permit separation of the flux as well as unalloyed metal, if any, thereby obtaining a clean melt of the alloy. This period is not required if the argon mantle is used.
  • the settled alloy then is transferred into a suitable mold to solidifyv Small amounts of a metal selected from the group consisting of thorium and aluminum may be employed in dfldhfldz Patented June 15, 1965 the beta phase magnesium-lithium-yttrium alloy. When used in amounts up to 5 percent these metals help to improve the stability of the alloy at elevated temperatures. These metals are integrated into the alloy in the same manner as described previously.
  • Example 1 A mixture of 83.8 grams of magnesium and 11.2 grams of lithium are melted in an open top crucible with a flux protective cover.
  • a suitable flux is one composed of 57 parts of KCl, 28 parts of CaCl 12.5 parts of BaCl and 2.5 parts of CaF
  • Five grams of yttrium are added to the mixture using a stirring rod with a one inch diameter flat disk fastened to the end. This allows for complete stirring of the melt and better control over the addition of the yttrium. After alloying has been efiected, the melt is allowed to remain undisturbed for a time to permit separation of flux as well as unalloyed metal, if any, thereby rendering a clean melt of the alloy.
  • the settled alloy is then transferred to a suitable mold, such as a sand or a metal mold, to solidify.
  • a suitable mold such as a sand or a metal mold
  • the ingots (1%" x 1%" x 3") are subsequently hot forged at a temperature of 500 F. to a y -inch thick plate.
  • Example 2 A mixture of 84.7 grams of magnesium, 11.3 grams of lithium, 2 grams of yttrium, and 2. grams of thorium are alloyed in the same manner as Example 1. The thorium is added in the same manner as the yttrium. The alloy is forged as in Example 1.
  • Example 3 A mixture of 83 grams of magnesium, 11 grams of lithium, 2 grams of yttrium, and 4 grams of aluminum are alloyed as in Example 2. The alloy is forged as in Example 1 but at a temperature of 550 F.
  • a magnesium base alloy consisting essentially of about 10 to 12 percent by weight lithium and about 4 to 6 percent by weight yttrium, the balance being magesium.
  • a magnesium base alloy consisting of about 10 to 12 percent by weight lithium, about 1 to 3 percent by weight yttrium, and about 1 to 5 percent by weight of a metal selected from the group consisting of thorium and aluminum, the balance being magnesium.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Manufacture And Refinement Of Metals (AREA)

Description

3,139,442 MAGNESlUM-LTTl-ITUM-YTTRIUM ALLQYS Paul D. Frost and Thomas G. lsyrer, Columbus, Ohio, assignors, by mesne assignments, to the United States of America as represented by the Secretary of the Army No Drawing. Filed May 27, 1963, Ser. No. 283,643 4 Claims. (Cl. 75122.7)
This invention relates to magnesium base alloys and more particularly to magnesium base alloys containing lithium and yttrium. Further, it concerns the beta phase of magnesium-lithium alloys employing yttrium.
Recent developments, particularly in the aircraft industry wherein stressed parts are subjected to elevated temperatures, have made it desirable to provide metals of light wei ht which have good stability and hardness at these elevated temperatures. Although the magnesium base alloys are among the lightest of the structural alloys, they have not met with wide acceptance in applications where stressed parts are exposed to elevated temperatures. Previous work has been done with magnesium-lithium alloys in an effort to increase hardness of the alloy at elevated temperatures without loss of the desirable properties such as lightness and ductility. These desired results are accomplished in this invention wherein the magnesium-lithium alloy is combined with yttrium to form an alloy with good stability and hardness at elevated temperatures.
Therefore it is an object of this invention to provide an improved magnesium base alloy.
it is a further object of this invention to provide a magnesium base alloy with improved hardness at elevated temperatures.
it is yet another object of the instant invention to provide a beta phase magnesium-lithium alloy with good stability at elevated temperatures.
These and other objects of this invention will become evident upon reading the more detailed description hereinbelow.
In general the objects of this invention are accomplished by alloying magnesium and lithium in the ratio by weight of 7.5 magnesium to l lithium, and adding amounts of yttrium not to exceed 6 percent of the total weight of the alloy. The ratio of 7.5 to 1 is necessary to insure the formation of the beta phase of the alloy wherein the lithium content cannot exceed 12 percent of the total weight of the alloy.
The order of addition of the metals to the magnesium is immaterial. The magnesium and lithium may be melted together and the yttrium added or the yttrium may be added to the molten magnesium prior to the addition of the lithium.
In accordance with the invention 10 to 12 percent by weight lithium and 4 to 6 percent by weight yttrium are alloyed with magnesium to make a 100 percent alloy. The magnesium and lithium are melted in an open top crucible with a flux protective cover. An argon mantle can be used instead of the flux protective cover. Any suitable flux known in the art can be used in this operation. The crucible is equipped with a stirring rod having a one inch flat disk fastened to the end. The yttrium is puddled into the solution using this stirring rod to insure complete stirring of the melt and better control over the addition of the yttrium. After alloying has been effected the melt is allowed to remain undisturbed for a time to permit separation of the flux as well as unalloyed metal, if any, thereby obtaining a clean melt of the alloy. This period is not required if the argon mantle is used. The settled alloy then is transferred into a suitable mold to solidifyv Small amounts of a metal selected from the group consisting of thorium and aluminum may be employed in dfldhfldz Patented June 15, 1965 the beta phase magnesium-lithium-yttrium alloy. When used in amounts up to 5 percent these metals help to improve the stability of the alloy at elevated temperatures. These metals are integrated into the alloy in the same manner as described previously.
This invention is further illustrated by the following examples Without being limited thereto.
Example 1 A mixture of 83.8 grams of magnesium and 11.2 grams of lithium are melted in an open top crucible with a flux protective cover. A suitable flux is one composed of 57 parts of KCl, 28 parts of CaCl 12.5 parts of BaCl and 2.5 parts of CaF Five grams of yttrium are added to the mixture using a stirring rod with a one inch diameter flat disk fastened to the end. This allows for complete stirring of the melt and better control over the addition of the yttrium. After alloying has been efiected, the melt is allowed to remain undisturbed for a time to permit separation of flux as well as unalloyed metal, if any, thereby rendering a clean melt of the alloy. The settled alloy is then transferred to a suitable mold, such as a sand or a metal mold, to solidify. The ingots (1%" x 1%" x 3") are subsequently hot forged at a temperature of 500 F. to a y -inch thick plate.
Example 2 A mixture of 84.7 grams of magnesium, 11.3 grams of lithium, 2 grams of yttrium, and 2. grams of thorium are alloyed in the same manner as Example 1. The thorium is added in the same manner as the yttrium. The alloy is forged as in Example 1.
Example 3 A mixture of 83 grams of magnesium, 11 grams of lithium, 2 grams of yttrium, and 4 grams of aluminum are alloyed as in Example 2. The alloy is forged as in Example 1 but at a temperature of 550 F.
The following table illustrates the hardess of each of the alloys in the above examples. An alloy of 12 percent lithium and 88 percent magnesium is used as a reference.
Diamond Pyramid Forg- Hardness, kgjmrn. Nominal Alloy Composition, ing
Wt. Percent Telmp F. F. F.
178 Mg-12 Li 450 33.2 4.2 0.9 196 Mgll.2 Li5Y 500 29.6 25.4 15.4 9.1 Mg-11.3L12Y Tl 599 45.9 19.5 9.6 4.9 197 Mg-11Li-2Y4Al 550 89.0 31.7 17.8 9.1
It is to be understood that the examples are for purposes of illustration and that the invention is limited only by the appended claims.
We claim:
1. A magnesium base alloy consisting essentially of about 10 to 12 percent by weight lithium and about 4 to 6 percent by weight yttrium, the balance being magesium.
2. A magnesium base alloy consisting of about 10 to 12 percent by weight lithium, about 1 to 3 percent by weight yttrium, and about 1 to 5 percent by weight of a metal selected from the group consisting of thorium and aluminum, the balance being magnesium.
3 4 3. The alloy of claim 2 wherein said metal is thqriurn. OTHER REFERENCES 4. The alloy of clalm 2 whereln sald metal 1s alumlnum. smith: College Chemistry, Sixth Edition Appletom References Cited by the Examiner Century Co., Inc., New York and London, pp. 569-570.
FOREIGN PATENTS 679' 747 9/52 G t B t 75 168 5 CARL D. QUARFORTH; Primary Examiner.
, rea r1 am 683,812 12/52 Great Britain 75-168 REUBEN EPSTEIN Examme

Claims (1)

  1. 2. A MAGNESIUM BASE ALLOY CONSISTING OF ABOUT 10 TO 12 PERCENT BY WEIGHT LITHIUM, ABOUT 1 TO 3 PERCENT BY WEIGHT YTTRIUM, AND ABOUT 1 TO 5 PERCENT BY WEIGHT OF A METAL SELECTED FROM THE GROUP CONSISTING OF THORIUM AND ALUMINUM, THE BALANCE BEING MAGNESIUM.
US283643A 1963-05-27 1963-05-27 Magnesium-lithium-yttrium alloys Expired - Lifetime US3189442A (en)

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Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3900296A (en) * 1973-10-01 1975-08-19 Dow Chemical Co Composite magnesium-titanium conductor
US3955933A (en) * 1972-02-29 1976-05-11 The United States Of America As Represented By The Secretary Of The Navy Magnesium-boron particulate composites
EP0491989A1 (en) * 1989-06-14 1992-07-01 Aluminum Company Of America Dual-phase, magnesium-based alloy having improved properties
US5156806A (en) * 1975-05-05 1992-10-20 The United States Of America As Represented By The Secretary Of The Navy Metal alloy and method of preparation thereof
JPH0625788A (en) * 1992-03-25 1994-02-01 Mitsui Mining & Smelting Co Ltd Light weight high strength magnesium alloy
JP3387548B2 (en) 1993-03-29 2003-03-17 三井金属鉱業株式会社 Manufacturing method of magnesium alloy molded product

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB679747A (en) * 1949-10-03 1952-09-24 Dow Chemical Co Improvements in magnesium-base alloys
GB683812A (en) * 1949-09-29 1952-12-03 Magnesium Elektron Ltd Improvements in or relating to magnesium base alloys

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB683812A (en) * 1949-09-29 1952-12-03 Magnesium Elektron Ltd Improvements in or relating to magnesium base alloys
GB679747A (en) * 1949-10-03 1952-09-24 Dow Chemical Co Improvements in magnesium-base alloys

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3955933A (en) * 1972-02-29 1976-05-11 The United States Of America As Represented By The Secretary Of The Navy Magnesium-boron particulate composites
US3900296A (en) * 1973-10-01 1975-08-19 Dow Chemical Co Composite magnesium-titanium conductor
US5156806A (en) * 1975-05-05 1992-10-20 The United States Of America As Represented By The Secretary Of The Navy Metal alloy and method of preparation thereof
EP0491989A1 (en) * 1989-06-14 1992-07-01 Aluminum Company Of America Dual-phase, magnesium-based alloy having improved properties
JPH0625788A (en) * 1992-03-25 1994-02-01 Mitsui Mining & Smelting Co Ltd Light weight high strength magnesium alloy
JP3261436B2 (en) 1992-03-25 2002-03-04 三井金属鉱業株式会社 Lightweight high strength magnesium alloy
JP3387548B2 (en) 1993-03-29 2003-03-17 三井金属鉱業株式会社 Manufacturing method of magnesium alloy molded product

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