Production of castable light rare earth rich light metal compositions from direct reduction processes
The disclosure concerns methods for making a composition comprising a light metal and an intermetallic comprising the light metal and a light rare earth element. The composition also may include a plurality of nanoparticles comprising an oxide of the light metal. The method includes directly reducing a light rare earth element precursor compound in a melt of the light metal, thereby forming the light rare earth element and nanoparticles of the light metal oxide.
1. A composition, comprising:
an alloy comprising (i) a light metal comprising aluminum, magnesium, or a combination thereof, and (ii) an intermetallic comprising the light metal and a light rare earth element, the light rare earth element comprising cerium, lanthanum, mischmetal comprising 47-70 wt % cerium and 25-45 wt % lanthanum, or any combination thereof, wherein at least a portion of the intermetallic is present as eutectic colonies with a fishbone structure; and
0.01-5 vol % of particles of an unreacted light rare earth element precursor compound comprising the light rare earth element, wherein the light rare earth element precursor compound comprises an oxide, a carbonate, a hydroxide, a chloride, a chlorite, a perchlorate, a fluoride, a fluorite, an oxalate, a sulfide, a sulfate, a sulfite, a phosphide, a phosphate or any combination thereof of the light rare earth element.
2. The composition of claim 1 , further comprising 0.01% (v/v) to 10% (v/v) of a plurality of nanoparticles comprising an oxide of the light metal, wherein the nanoparticles have an average size within a range of 10 nm to 500 nm.
3. The composition of claim 2 , wherein:
(i) the light metal comprises aluminum, and the nanoparticles comprise aluminum oxide; or
(ii) the light metal comprises magnesium, and the nanoparticles comprise magnesium oxide; or
(iii) the light metal comprises a combination of aluminum and magnesium, and the nanoparticles comprise a combination of aluminum oxide, magnesium oxide, or magnesium aluminate, or any combination thereof.
4. The composition of claim 1 , wherein the composition comprises 2 wt % to 60 wt % of the light rare earth element.
5. The composition of claim 1 , wherein the light rare earth element comprises cerium.
6. The composition of claim 1 , wherein the alloy further comprises silicon, zirconium, manganese, zinc, iron, nickel, copper, or any combination thereof.
7. The composition of claim 1 , wherein the light rare earth element comprises cerium, and the unreacted light rare earth element precursor compound comprises cerium oxide, cerium carbonate, cerium hydroxide, or any combination thereof.
8. The composition of claim 1 , wherein the particles of the unreacted light rare earth element precursor compound have an average size within a range of from 10 nm to 500 μm.
9. A method of making a composition, comprising:
melting a light metal to form a melt, the light metal comprising aluminum, magnesium, or a combination thereof;
agitating the melt to produce a vortex, an eddy current, cavitation, charge buildup, or any combination thereof within the melt;
adding a powder comprising particles of a light rare earth element precursor compound to the melt while agitating the melt to reduce at least a portion of the light rare earth element precursor compound and form a molten composition comprising the light metal, the light rare earth element, and particles of unreacted light rare earth element precursor compound, the light rare earth element comprising cerium, lanthanum, mischmetal comprising 47-70 wt% cerium and 25-45 wt% lanthanum, or any combination thereof, and the light rare earth element precursor compound comprising an oxide, a carbonate, a hydroxide, a chloride, a chlorite, a perchlorate, a fluoride, a fluorite, an oxalate, a sulfide, a sulfate, a sulfite, a phosphide, a phosphate or any combination thereof of the light rare earth element; and
cooling the molten composition to produce a composition comprising (i) an alloy of the light metal and an intermetallic comprising the light metal and the light rare earth element, wherein at least a portion of the intermetallic is present as eutectic colonies with a fishbone structure, and 0.01-5 vol% of particles of the unreacted light rare earth element precursor compound comprising the light rare earth element.
10. The method of claim 9 , wherein agitating the melt comprises:
(i) mechanically or magnetically stirring the melt; or
(ii) ultrasonication of the melt; or
(iii) application of a direct or alternating electrical current through the melt; or
(iv) any combination of (i), (ii), and (iii).
11. The method of claim 9 , wherein adding the powder comprising the light rare earth element precursor compound to the melt further comprises:
fluidizing the powder with a gas to provide a fluidized powder; and
injecting the fluidized powder into the melt below an upper surface of the melt.
12. The method of claim 9 , wherein adding the powder comprising the light rare earth element precursor compound comprises:
selecting an amount of the powder comprising the light rare earth element precursor compound; and
serially adding fractions of the selected amount of the powder comprising the light rare earth element precursor compound to the melt at intervals while agitating the melt until all of the selected amount has been added.
13. The method of claim 12 , wherein serially adding fractions of the selected amount of the powder comprising the light rare earth element precursor compound to the melt at intervals further comprises:
(a) adding a first fraction of the selected amount;
(b) agitating the melt for a period of time to reduce at least some of the first fraction;
(c) adding a subsequent fraction of the selected amount;
(d) agitating the melt for a subsequent period of time to reduce at least some of the subsequent fraction; and
(e) repeating steps (c) and (d) until all of the selected amount has been added.
14. The method of claim 9 , wherein the light rare earth element precursor compound comprises cerium oxide, cerium carbonate, cerium hydroxide, or any combination thereof.
15. The method of claim 9 , wherein:
(i) the molten composition further comprise particles comprising an oxide of the light metal, the method further comprising removing at least some of the particles comprising the oxide of the light metal from the molten composition before cooling the molten composition; or
(ii) the method further comprises removing at least some of the particles comprising unreacted light rare-earth element precursor compound from the molten composition before cooling the molten composition; or
(iii) both (i) and (ii).
16. The method of claim 15 , wherein removing at least some of the particles comprising the oxide of the light metal or at least some of the particles comprising unreacted light rare earth element precursor compound comprises:
passing gas bubbles through the molten composition, whereby solid particles within the molten composition are conveyed by the gas bubbles to an upper surface of the molten composition, the solid particles comprising the particles comprising the oxide of the light metal, the particles comprising unreacted light rare earth element precursor compound, or both; and
removing the solid particles from the upper surface of the molten composition.
17. The method of claim 16 , wherein the gas bubbles comprise nitrous oxide, chlorine, nitrogen, or argon.
18. The method of claim 9 , wherein the method is a continuous or semi-continuous method, the method further comprising:
continuously adding light metal or serially adding amounts of the light metal to the melt at intervals with continuous agitation;
continuously adding powder comprising the light rare earth element precursor compound or serially adding amounts of the powder comprising the light rare earth element precursor compound to the melt at intervals with continuous agitation;
continuously transferring molten composition to a die caster or serially transferring portions of the molten composition at intervals to the die caster;
transferring molten composition from the die caster to a series of molds; and
cooling the molten composition in the molds to produce the composition.
19. A composition made by the method of claim 9 .