Manganese aluminium silicon-lithium rare earth alloy and preparation method thereof
Technical field:
The present invention relates to a kind of magnalium silicon-lithium rare earth alloy for building and preparation method thereof.Belong to the aluminium-magnesium alloy technical field.
Background technology:
Traditional aluminium alloy has aerospace, automobile aluminium-lithium alloy and aluminium-magnesium alloy for building etc.
The ordination number of lithium is 3, density 0.53g/cm
3, be the lightest in the metal.Aluminium-lithium alloy (Al-Li-Cu-Zr is an alloy) contains 1%~2% lithium, can make alloy density reduce by 5%~6%, and rigidity increases by 13%, increases by 15%~20% than rigidity.Aluminium-lithium alloy is bigger than rigidity, specific tenacity, especially significantly improved the alloy corrosion resistance energy of aluminium-magnesium alloy when aluminium content is higher, noticeable especially is than the height of rigidity than other duralumin systems, titanium alloy, ferrous materials, and this is very suitable concerning the structured material that requires high rigidity.Obtained application more and more widely in aerospace, automobile and field.But because elemental lithium is very active, very easily oxidation even burning in atmosphere, also extremely strong with the bonding force of hydrogen, and react with furnace lining material easily, the erosion crucible, a large amount of slag inclusions of formation are involved in the ingot casting.Very easily segregation of lithium itself in the fusion-casting process simultaneously also have the danger of blast during casting with water cooling, so the production difficulty of alloy is very big, and Al-Li alloy is melting and casting according to a conventional method at all.
But because aluminium-magnesium alloy for building adopts extrusion molding processing usually, require alloy that higher flowability and castability are arranged, consider that from castability and mechanical property the most frequently used cast magnesium alloys is to contain Al to reach 9% AZ91 type magnesium alloy (its principal constituent scope is: Al:8.5-9.5%; Mn:0.17-0.4%; Zn:0.45-0.9%; Si:<0.05%; Impurity:<0.01%).From the desired alloy high workability of casting forming high rate of finished products and castability consider alloy to contain the Al amount high more good more, so the Al amount that contains of magnesium alloy requires 〉=9%.
Summary of the invention:
The objective of the invention is to solidity to corrosion demand, provide Li content in the high Al content range of 1-2%, anti-corrosion manganese aluminium silicon-lithium rare earth alloy and preparation method thereof at magnalium.
The object of the present invention is achieved like this: a kind of manganese aluminium silicon-lithium rare earth alloy, it is characterized in that it consists of the element that contains following mass percent: Al:10-11.5, Mn:0.1-1.0, La:0.1-0.8, Li:1-2, Ce:0.1-0.8, Pr:0.05-0.3, Zn:0.1-0.5, Sr:0.2-1.5, Si:0.08-0.1, the remainder of above-mentioned magnesium alloy is made up of Mg and unavoidable impurities, its raw material is: Mg, Al, Zn, Li and Si adopt the technical pure metal, Mn adopts the Al-Mn master alloy, La, Pr, it is the rich La of Mg-of 15-25% that Ce adopts content of rare earth, the rich Pr of Mg-, the master alloy of rich Ce of Mg-and the rich LaPrCe of Mg-, Sr adopts technical pure Sr, and La: Ce: Pr=5.5-6.5: 2.5-3.5 in the rich LaPrCe master alloy of Mg-: 1.
The unavoidable impurities element mainly is in this magnesium alloy: Cu, Fe, Ni.Its content is: Cu≤0.004%; Ni≤0.002%; Fe≤0.004%.
The preparation method of manganese aluminium silicon-lithium rare earth alloy, the specific embodiment of this method is: at protective atmosphere CO
2: N
2=1.3-1.7: in 1 the smelting furnace, first fusing Mg, Al, Li and Si, treat Mg, Al, Li and Si fusing after, the master alloy that adds Mg-La, Mg-Pr, Mg-Ce and Mg-LaPrCe again, Al-Mn master alloy and Zn add metal Sr at last, and smelting temperature is 700 ℃ ± 10 ℃, after treating that alloying element all melts, be warming up to 740 ℃ ± 10 ℃, left standstill 30 ± 10 minutes, make the alloy liquid temp reduce to 710 ℃ ± 10 ℃ then, skim ingot casting or die casting.
Alloy provided by the invention has excellent corrosion resistant performance, and the corrosion rate of its salt-fog test is 0.1 milligram/centimetre
2About it.(seeing Table 1)
The corrosion rate of a, salt-fog test
The solidity to corrosion of alloy adopts the corrosion rate of general salt-fog test to measure.Alloy is at the salt fog of 5%NaCl, and 35 ℃ corrosion is after 100 hours down, and the weightlessness of measuring before and after corroding is calculated corrosion rate.The corrosion rate of alloy provided by the invention and comparative alloy AZ91 (Mg-9Al) and Mg-9Al-1Re alloy is as shown in showing.
B, electrochemical AC impedance are measured
The polarization resistance Rp value that electrochemical AC impedance is measured is represented corrosion resistance (its inverse is corrosion rate), and the Rp value is big more, and the expression alloy is corrosion-resistant more.The Rp value of the embodiment of the invention and comparative alloy is as shown in table 2.
Alloy that table 1. embodiment of the invention provides and comparative alloy Mg-9Al and Mg-9Al-1Re (Re is about 50% mishmetal for Ce content) are at the corrosion rate of 35 ℃ of salt-fog tests of 5%NaCl.
Alloy |
Corrosion rate (milligram/centimetre
2My god)
|
Comparative alloy AZ91 (Mg-9Al) |
>10 |
The present invention |
0.06 |
The Rp value that table 2. magnalium provided by the invention and comparative alloy electrochemical impedance are measured
Alloy |
Alternating-current impedance (Rp) value (Ω cm
2)
|
Comparative alloy Mg-9Al alloy |
263 |
The present invention |
1356 |
As can be seen from Table 2: the Rp value of alloy provided by the invention is apparently higher than correlated AZ91 alloy (Mg-9Al).Therefore alloy provided by the invention has stronger solidity to corrosion.
Therefore, the solidity to corrosion of alloy provided by the invention significantly surpasses general AZ91 alloy, and it is the Mg-Al alloy with excellent corrosion resistance.
In addition, the mechanical property of alloy provided by the invention and comparative alloy (AZ91) is as shown in table 3.
The mechanical property of table 3. alloy provided by the invention and comparative alloy (AZ91)
Alloy |
The room temperature tensile strength sigma
b(MPa)
|
Unit elongation (δ %) |
Impelling strength Ak (J joule) |
The present invention |
>270 |
>8 |
>4 |
Comparative alloy AZ91 |
>160 |
>3 |
>4 |
Therefore, magnesium alloy contrasts such as high aluminium content lithium-aluminium alloy provided by the invention and AZ-91 have fabulous solidity to corrosion.
(the present invention and traditional Al-Li-Cu-Zr are the alloy phase ratio, and safe range of stress improves 8%, and nominal threshold value improves 30%, and the intrinsic threshold value improves 50%, and stretching plastic improves 1/3~1/2, and fracture toughness property improves 20MPa/m, improves 2 times creep rupture life.)
Embodiment:
Below by specific embodiment, further illustrate substantive distinguishing features of the present invention and marked improvement, but the present invention only is confined to embodiment by no means.
Embodiment 1:
Alloy preparation composition (mass percent) is: Al:11%, La:0.8%, Ce:0.8%, Li:1.4%, Pr:0.30%, Mn:0.5%, Zn:0.4%, Sr:1.5%, Si:0.08%.The unavoidable impurities element is restricted to: Cu≤0.004%, and Ni≤0.002%, Fe≤0.004%, all the other are Mg.Adopt technical pure Mg, industrial pure Al, technical pure Li, technical pure Si, (total amount of LaPrCe accounts for 20% to the Mg-LaPrCe master alloy, La: Ce: Pr=6 wherein: 3: 1), and the Mg-Ce master alloy (Ce: 20%), Mg-Pr master alloy (Pr:10%), the Al-Mn master alloy, industrial-purity zinc, metal Sr presses the mentioned component alloyage.At protective atmosphere (CO
2: N
2=150: 100) in the Mg alloy smelting furnace, fusing Mg, Al, Li and Si earlier, treat Mg, Al, Li and Si fusing after, add Mg-LaPrCe again, Mg-Ce, Mg-Pr, Al-Mn master alloy and Zn add metal Sr at last, treat that alloying element is all after the fusing, (being about 710 ℃), heat up, to 730 ℃, left standstill 30 minutes, controlled temperature is no more than 750 ℃, and the alloy liquid temp is reduced to about 710 ℃, skim ingot casting or die casting.When carrying out ingot casting, the teeming temperature of alloy is 680-720 ℃.When carrying out die casting, the alloy liquid temp is controlled at 690~710 ℃ carries out high-pressure casting and become magnesium alloy product.The present embodiment alloy is 0.05 milligram/centimetre at the corrosion rate of 5%NaCl salt-fog test
2My god, its room temperature tensile strength is 276MPa, and unit elongation is 9%, and impelling strength is 6J.
Embodiment 2:
Alloy preparation composition (mass percent) is: Al:11.5%, La:0.8%, Ce:0.8%, Li:1.8%, Pr:0.30%, Mn:0.5%, Zn:0.4%, Sr:0.08%, Si:0.08%.The unavoidable impurities element is restricted to: Cu≤0.004%, and Ni≤0.002%, Fe≤0.004%, all the other are Mg.Adopt technical pure Mg, industrial pure Al, technical pure Li, technical pure Si, (total amount of LaPrCe accounts for 20% to the Mg-LaPrCe master alloy, La: Ce: Pr=6 wherein: 3: 1), Mg-Ce master alloy (Ce:20%), Mg-Pr master alloy (Pr:10%), the Al-Mn master alloy, industrial-purity zinc, metal Sr presses the mentioned component alloyage.At protective atmosphere (C0
2: N
2=150: 100) in the Mg alloy smelting furnace, fusing Mg, Al, Li and Si earlier, treat Mg, Al, Li and Si fusing after, add Mg-LaPrCe again, Mg-Ce, Mg-Pr, Al-Mn master alloy and Zn add metal Sr at last, treat that alloying element is all after the fusing, (being about 710 ℃), heat up, to 730 ℃, left standstill 30 minutes, controlled temperature is no more than 750 ℃, and the alloy liquid temp is reduced to about 710 ℃, skim ingot casting or die casting.When carrying out ingot casting, the teeming temperature of alloy is 680-720 ℃.When carrying out die casting, the alloy liquid temp is controlled at 690~710 ℃ carries out high-pressure casting and become magnesium alloy product.The present embodiment alloy is 0.03 milligram/centimetre at the corrosion rate of 5%NaCl salt-fog test
2My god, its room temperature tensile strength is 283MPa, and unit elongation is 8%, and impelling strength is 7J.