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Al–Li–Zn

Aluminium – Lithium – Zinc

Oksana Bodak

Literature Data

The research on this system started in 1942 when [1942Wei] established the temperature and compositionof a ternary eutectic in the Zn corner. One year later [1943Bad] investigated the triangle Al-LiAl-Zn bythermal and microscopic analyses. They found two ternary compounds, J1 and J3, in the LiAl-Zn sectionand gave eight vertical and two isothermal sections. The J1 phase has been confirmed by [1963Che] and theregion of its homogeneity has been determined more accurately; however, these authors found J1 to be inequilibrium with (Zn) neglecting the J3 phase. [1987Dub] and [1989Aud] reported a stable phase to existin the vicinity of J4, Li3ZnAl5, not far from the Al rich end of the J1 domain. Metastable icosahedralquasicrystals are formed in this system by rapid solidification [1986Cas, 1987Che] or as grain boundaryprecipitates through solid - solid transformations [1987Cas] with compositions close to the stable J1 phase.The substitution behavior of additional elements in the L12 type metastable compound of Li3Al (*´ phase)was reported in [1994Hos]. In 1995 a critical review was made inn the MSIT evaluation programs, coveringthe literature published until 1992, [1995Pav]. Isothermal section of the system at 197°C and crystal structures of compounds were investigated andpublished in [1993Pav, 1995Dmy, 1996Dmy, 1999Pav]. Alloys of the Al-Li-Zn system were prepared byarc-melting pieces of the pure metals (lithium with a purity 98.2 mass%, zinc with a purity 99.98 mass%,aluminium with a purity 99.99 mass%) under argon atmosphere. The alloys were annealed at 197°C for 400hours in tantalum containers in evacuated quartz ampoules, quenched in cold water and examined by X-raydiffraction analysis. There are measurements of the enthalpy of mixing of liquid Al-Li-Zn ternary made byhigh temperature mixing calorimeter in the temperature range 456 - 682°C, [1997Kim]. They used their datain an association model to calculate the thermodynamic mixing functions of the ternary alloys on the basisof the enthalpy of mixing of the binary systems. Aluminium of purity 99.9%), 99.9% pure lithium and zincof 99.999% were used to prepare the alloy samples for these measurements, executed under pure argon gasat atmospheric pressure.

Binary Systems

For the Al-Li system phase relations are accepted here as reported by [2003Gro]. For the descriptions of theAl-Zn and Li-Zn phase diagrams the versions given in [Mas2] are accepted.

Solid Phases

The data for the solid phases are given in Table 1. The quasicrystalline phases are formed by rapidsolidification or as grain boundary precipitates by a solid-state reaction in the J1 phase region [1997Kim].The J1 phase has a high solubility of zinc (16.7-43.3 at.% Zn at 32 at.% Li) and is formed through aperitectic reaction at higher temperature than the J3 and J4 phases [1997Kim]. According to [1993Pav,1996Dmy, 1999Pav] three ternary compounds are formed in this system: (a) the J1 phase,Li1+xZn0.5-1.5Al1.5-0.5 with a large homogeneity range which includes the earlier reported composition J1,Li26Al6(Zn1-xAlx)49 (b) the J3 phase, LiZn3Al with an unidentified structure and (c) the J4 phase, Li3ZnAl5.Another compound J2 on the 50 at.% Li section is reported in the work of [1996Dmy].

Pseudobinary Systems

The section LiAl-Zn shown in Fig. 1 is pseudobinary [1943Bad]. The solidus and the liquidus of the LiAlphase in Fig. 1 are slightly corrected to agree with the congruent melting point of this phase in the binarysystem.

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Al–Li–Zn

The LiAl - Li2Zn3 section has been reported by [1943Bad] as pseudobinary with continuous solid solubility.However this is unlikely because LiAl and Li2Zn3 have different crystal structures, and this contradicts tothe existence of the J2 phase proposed by [1996Dmy].

Invariant Equilibria

The invariant equilibria established within the triangle Al-LiAl-Zn and in the pseudobinary section LiAl-Zn[1943Bad] are listed in Table 2. An additional four-phase equilibrium at 423°C has been proposed by[1943Bad] following the existence of an intermediate phase in the Al-Zn system. However, in the presentlyaccepted Al-Zn binary this phase does not exist and therefore the invariant reaction at 423°C is eliminatedfrom the reaction scheme and liquidus surface in this evaluation. The reaction scheme is shown in Fig. 2.The temperature and the concentration of the ternary eutectic E1 are reported with some uncertainty, 355°Cgiven by [1943Bad] and 364.25°C. In Fig. 2 and Table 2 the values of [1942Wei] are preferred.

Liquidus Surface

Figure 3 shows the liquidus surface of the Al-LiAl-Zn partial system the diagram given by [1943Bad]. Ithad to be amended to match with the accepted binary equilibrium diagrams Al-Zn [Mas2] and Al-Li[1989Che]. The ternary eutectic is incorporated using the data given by [1942Wei].

Isothermal Sections

Figure 4 shows the amended partial isothermal section Al-LiAl-Zn at 350°C according to [1943Bad]. Thesection now is compatible with the accepted binary systems Al-Li [1989Che] and Al-Zn [Mas2] andcoherent with [1996Dmy] for which the $ phase extends in the ternary system along the 50 at.% Li. Thehomogeneity region of the J1 phase follows [1963Che] and may be expressed by the approximate formulaLiZn0.5+xAl1.5+x (0 < x < 0.7). There is no experimental evidence for a large width of the J1 field, so the Licontent may be accepted as 34-35 at.% as given by [1943Bad]. [1963Che] found the J1 phase in equilibriumwith (Zn) neglecting J3. The isothermal section of the system at 193°C according to [1996Dmy] is shownin Fig. 5. No significant solubilities of Al in binary Li-Zn compounds have been detected.

Thermodynamics

The values )H(xC) of liquid Al-Li-Zn alloys were determined at different temperatures along four sectionskeeping the concentration ratios of two components constant [1997Kim]: (a) Al0.25Zn0.75-Li, (b)Al0.50Zn0.50-Li, (c) Al0.70Zn0.30-Li and (d) Al0.75Li0.25-Zn. They are plotted in Figs. 6 and 7. The )Hvalues of the ternary liquid alloys can be obtained by adding the )H value of the binary boundary systems:)H(xA/xB = const., xC) = (1 - xC) )H(xA/xB = const.) + )Hi(xC)(xA/xB = const.)

For the section Al0.25Zn0.75-Li the agreement between the measured and calculated values is within theexperimental error. For other concentration section the experimental )H values exhibit more negativevalues compared with the calculated ones. These deviations could be caused by a negative contribution tothe enthalpy of mixing due to the presence of additional ternary interactions or additional ternary associatesin the melt which have not been taken into account in the model calculation. The presence of additionalternary interaction in the liquid state is supported by the existence of at least three ternary intermetallicphases in this system [1995Pav]. The difference between measured and calculated values of )H is shownin Fig. 8 together with the position of the ternary intermetallic phases. Figure 8 shows that the deviationamounts to - 3.5 kJ@mol-1 in the concentration region where the J1 phase exists, which points to additionalternary interaction in this concentration region. In the region of the ternary J2 and J3 phase the deviation issmall in comparison to that in the J1 phase region. This indicates that the ternary interactions in theseregions are relatively weak and the influence of the ternary J1 phase is predominant for liquid Al-Li-Znalloys.

δi∑

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Al–Li–Zn

Notes on Materials Properties and Applications

Al-Li base alloys have received considerable attention as potential lightweight replacements forconventional Al base alloys in aerospace applications. The addition of 1.8-2.1% Li remarkably alter theprecipitation behavior of the Al-Cu-Mg-Zn alloys which are the highest strength aluminum alloys[2000Wei].

References

[1942Wei] Weisse, E., Blumenthal, A., Hanemann, H., “Results of an Investigation of Eutectic ZincAlloys” (in German), Z. Metallkd., 34(9), 221 (1942) (Equi. Diagram, Experimental, 9)

[1943Bad] Badaeva, T.A., Sal’dau, P.Y., “Physico-Chemical Investigation of Alloys of Aluminiumwith Zinc and Lithium” (in Russian), Zhur. Obshchey Khimii, 13(9/10), 643-660 (1943)(Equi. Diagram, Experimental, 23)

[1963Che] Cherkashin, E.E., Kripyakevich, P.I., Oleksiv, G.I., “Crystal Structures of TernaryCompounds in Li-Cu-Al and Li-Zn-Al Systems” (in Russian), Sov. Phys., -Crystallogr.,8(6), 681-685 (1964), translated from Kristallografiya, 8(6), 846-851 (1963) (Crys.Structure, Experimental, 11)

[1986Cas] Cassada, W.A., Shen, Y., Poon, S.J., Shiflet, G.J., “Mg32(Zn,Al)49-Type IcosahedralQuasicrystals Formed by Solid-State Reaction and Rapid Solidification”, Phys. Rev. B:Solid State, 34(10), 7413-7416 (1986) (Experimental, 17)

[1987Cas] Cassada, W.A., Shiflet, G.J., Poon, S.J., “Quasicrystalline Grain Boundary Precipitates inAl Alloys Through Solid-Solid Transformations”, J. Microsc., 146(3), 323-335 (1987)(Experimental, 26)

[1987Che] Chen, H.S., Phillips, J.C., Villars, P., Kortan, A.R., Inoue, A., “New Quasicrystals of AlloysContaining s, p and d Elements”, Phys. Rev. B, Cond. Matter, 35B(17), 9326-9329 (1987)(Crys. Structure, Experimental, 18)

[1987Dub] Dubost, B., Audier, M., Jeanmurt, P., Lang, J.M., Sainfort, P., “Structure of StableIntermetallic Compounds of the AlLiCu(Mg) and AlLiZn(Cu) Systems”, J. Phys., Colloq.,48C3(9), 497-504 (1987) (Crys. Structure, Experimental, 16)

[1989Aud] Audier, M., Janot, C., De Boissieu, M., Dubost, B., “Structural Relationships inIntermetallic Compounds of the Al-Li-(Cu, Mg, Zn) System”, Philos. Mag. B, 60(4),437-466 (1989) (Crys. Structure, Experimental, 34)

[1989Che] Chen, S.-W., Jan, C.- H., Lin, J.-C., Chang, Y. A., “Phase Equilibria of the Al-Li BinarySystem”, Metall. Trans., 20A(11), 2247-2258 (1989) (Equi. Diagram, Experimental, #, 59)

[1993Pav] Pavlyuk, V.V., “Synthesis and Crystal Chemistry of Lithium Intermetallic Compounds”,Doct. Thesis, Univ. L’viv, 1-35 (1993) (Equi. Diagram, Crys. Structure, Experimental,Review, 49)

[1994Hos] Hosoda, H., Sato, T., Tezuka, H., Mishima, Y., Kamio, A., “Substitution Behavior ofAdditional Elements in the L1(2)-Type Al3Li Metastable Phase in Al-Li Alloys” (inJapanese), J. Jpn. Inst. Met., 58(8), 865-871 (1994) (Crys. Structure, Thermodyn.,Theory, 26)

[1995Pav] Pavlyuk, V., Bodak, O., MSIT Ternary Evaluation Program, in MSIT Workplace,Effenberg, G. (Ed.), MSI, Materials Science International Services GmbH, Stuttgart;Document ID: 10.16727.1.20, (1995) (Crys. Structure, Equi. Diagram, Assessment, 9)

[1995Dmy] Dmytriv, G.S., “Isothermal Section of the Phase Diagram of the System Li-Zn-Al at 470 K”(in Ukrainian), Lvivski Khimichni Chytannya Naukova-Praktychna Konferentsiya, LDU,108 (1995) (Equi. Diagram, Experimental, 0)

[1996Dmy] Dmytriv, G.S., “Phase Equilibria and Crystal Structure of Compounds in Mg-Li-Si,Ca-Li-{Si, Ge}, Al-Li-{Si, Ge, Sn}, Zn-Li-{Al, Sn}” (in Ukrainian), Summary of the Thesisfor Candidate Science Degree, Lviv, 1-23 (1996) (Crys. Structure, Equi. Diagram,Experimental, 10)

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Al–Li–Zn

[1997Kim] Kim, Y.B., Sommer, F., “Calorimetric Measurement of Liquid Aluminium-Lithium-ZincAlloys”, Thermochim. Acta, 291, 27-34 (1997) (Equi. Diagram, Thermodyn.,Experimental, 16)

[1999Pav] Pavlyuk, V.V., Dmytriv, G.S., Bodak, O.I., Stepien-Damm, J., “New Variant of theStructure of the Li1+xZn0.5-1.5Al1.5-0.5 Intermetallic Compound”, Materials Structure, 6(2),146-148 (1999) (Crys. Structure, Experimental, 4)

[2000Wei] Wei, B.C., Chen, C.Q., Huang, Z., Zhang, Y.G., “Aging Behavior of Li ContainingAl-Zn-Mg-Cu Alloys”, Mat. Sci. Eng. A, 280(1), 161-167 (2000) (Mechan. Prop.,Experimental, 9)

[2003Gro] Gröbner, J., “Al-Li (Aluminium-Lithium)”, MSIT Binary Evaluation Program, in MSITWorkplace, Effenberg, G. (Ed.), MSI, Materials Science International Services GmbH,Stuttgart; Document ID: 20.13517.1.20, (2003) (Equi. Diagram, Crys. Structure,Assessment, 29)

Table 1: Crystallographic Data of Solid Phases

Phase/Temperature Range [°C]

Pearson Symbol/Space Group/Prototype

Lattice Parameters[pm]

Comments/References

(Li)< 180.6

cI2Im3mW

a = 351.0 pure Li at 25°C [V-C2]

(Zn)< 419.58

hP2P63/mmcMg

a = 266.50c = 494.70

at 25°C [Mas2]

(Al)< 660.45

cF4Fm3mCu

a = 404.96 pure Al at 25°C [Mas2]Dissolves up to 15 at.% Li

*, Li9Al4< 347 - 275

mC26C2/mLi9Al4

a = 1915.51b = 542.88c = 449.88$ = 107.671°

[2003Gro]

*´, Li9Al4< 275

? ? [Mas2]

Li3Al2< 520

hR15R3mLi3Al2

a = 450.8c = 1426

[2003Gro]60 to 61 at.% Li [Mas2]

$, LiAl< 700

cF16Fd3mNaTl

a = 637 at 50 at.% Li [2003Gro]45 to 55 at.% Li [Mas2]

"´, LiAl3< 190 - ~120

cP4Pm3mCu3Au

a = 403.8 Metastable [2003Gro]

"LiZn4< 245

hP2P63/mmcMg

a = 278.8c = 439.4

[V-C2], [Mas2]

$LiZn4481 - 65

hP2P63/mmc

- [Mas2]

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Al–Li–Zn

Table 2: Invariant Equilibria

"Li2Zn5< 268

hP* a = 437.0c = 251.5

[V-C2], [Mas2]

$Li2Zn5502 - 168

- - [Mas2]

LiZn2< 93

- - [Mas2]

"Li2Zn3< 174

cP5 a = 427 [V-C2], [Mas2]

$Li2Zn3520 - 160

- - [Mas2]

LiZn< 177

cF16Fd3mNaTl

a = 623.2 [V-C2], [Mas2]

* J1,Li1+gZn0.5-1. 3Al1.5-0.7

cI160Im3LiCuSi

a = 1401.7 " 0.3 toa = 1390.4 " 0.3

[1999Pav]single crystal data

* J2,LiZn0.6-0.8Al0.4-0.2

cF16Fd3mNaTl

a = 625.7 toa = 621.3

[1996Dmy]

* J3,. LiZn3Al< 490

- - [1943Bad], [1996Dmy]not found by [1963Che], [1996Dmy]

* J4, . Li3ZnAl5P42/mmc

a = 1391c = 8205a = 1390c = 8245

[1987Dub]

sample compositionLi0.33 Zn0.11Al0.56[1989Aud]

Reaction T [°C] Type Phase Composition (at.%)Al Li Zn

L + $ º J1 + (Al) 452 U1 L$

J1 (Al)

33.2< 41.5< 35< 86

17.539.5357

49.319.0>30 >7 >

L + J1 º J3 + (Al) 368 U2 LJ1J3(Al)

15.1< 33.3< 20< 88

9.3 33.3204

75.633.3 >60 >8 >

L º (Al) + (Zn) + J3 355 a) E1 L(Al)(Zn)J3

13.0< 88.0< 3.0< 16.8

8.22.02.016.8

78.810.0 >95.0 >66.4 >

Phase/Temperature Range [°C]

Pearson Symbol/Space Group/Prototype

Lattice Parameters[pm]

Comments/References

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Al–Li–Zn

Note: values in brackets < > are estimated.a) Value given by [1943Bad], 364°C after [1942Wei].

L + $ º J1 580 p1 L$

J1

32.2< 41< 35

32.24135

35.618.0 >30 >

L + J1 º J3 490 p2 LJ1J3

18.6< 33.3< 20

18.633.320

62.833.3 >60 >

L º J3 + (Zn) 369 e3 LJ3(Zn)

11< 16.8< 2.5

1116.82.5

7866.4 >95.0 >

Reaction T [°C] Type Phase Composition (at.%)Al Li Zn

10 20 30 40

300

400

500

600

700

Zn Li 50.00Zn 0.00Al 50.00Al, at.%

Te

mp

era

ture

, °C

L

β

τ1

580°C

490°C

369°C

419.58°C

700°C

(Zn)

τ3

Fig. 1: Al-Li-Zn.The pseudobinary system Zn - LiAl

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Al–Li–Zn

Fig

. 2:

Al-

Li-

Zn

. R

eact

ion s

chem

e

Al-

LiA

lA

l-Z

nL

iAl-

Zn

Al-

LiA

l-Z

n

l (

Al)

+ (

Zn)

38

1e 2

l (

Al)

+ β

60

0e 1

L +

βτ 1

+ (

Al)

45

2U

1

L +

βτ 1

58

0p

1

(Al)

´´

(A

l)´

+ (

Zn)

27

7e 4

L +

τ1

τ 3

49

0p

2

L (

Zn

) +

τ3

36

9e 3

L +

τ1

τ 3 +

(A

l)3

68

U2

L (

Al)

+ (

Zn)

+ τ

33

55

E1

(Al)

´´

(A

l)´+

(Zn

)+τ 3

27

5E

2

L+

(Al)

+τ 1

(Al)

+(Z

n)+

τ 3

(Al)

´´+

(Zn)+

τ 3

L+

τ 1+

τ 3

β +

τ1 +

(A

l)

L+

(Al)

+τ 3

τ 1+

τ 3+

(Al)

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Al–Li–Zn

20

40

60

80

20 40 60 80

20

40

60

80

Li Zn

Al Data / Grid: at.%

Axes: at.%

β

(Al)´

(Zn)

τ3

τ1

(Al)´´+τ

3 +(Zn)

(Al)´+τ1+τ

3

(Al)´´

β+(Al)´

(Al)

´+τ 1

20

40

60

80

20 40 60 80

20

40

60

80

Li Zn

Al Data / Grid: at.%

Axes: at.%

LiAl

(Al)

β

τ1

τ3

(Zn)

e1

p1

U1

p2

e3

U2 E

1

e2

600

550

500

470

450

430 420

380400

650

700 600

Fig. 4: Al-Li-Zn.Partial isothermal section at 350°C

Fig. 3: Al-Li-Zn.Partial liquidus surface

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Al–Li–Zn

20

40

60

80

20 40 60 80

20

40

60

80

Li Zn

Al Data / Grid: at.%

Axes: at.%(Al)

τ1

τ3

τ2

β

Li3Al

2

δ´

βLi2Zn

3 βLi2Zn

5 βLiZn4

(Zn)αLiZn4

αLi2Zn

5

-15

-10

-5

0

5

0 20 40 60 80 100

Al

Zn

Li

100-

0.00

x

xLi, at.%

∆ mix

H,

kJ

mo

l-1·

Li

5

=30 (610°C)x

x=75 (518°C)

x=50 (554°C)

Fig. 5: Al-Li-Zn.The isothermal section at 193°C

Fig. 6: Al-Li-Zn.Experimental enthalpy of mixing for ternary undercooled liquid alloys

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Al–Li–Zn

5

0

-5

-10

0 20 40 60 80 100

∆ mix

H,

kJ

mo

l-1·

Al

Zn

Li

Li, at.%75.0000.0025.00

Li

20

40

60

80

20 40 60 80

20

40

60

80

Li Zn

Al Data / Grid: at.%

Axes: at.%

-3.5

9

-1.5

-1.0

τ2

τ3

τ1

experimental

calculated

Fig. 7: Al-Li-Zn.Enthalpy of mixing of (Al0.75Li0.25)1-xZnx ternary liquid and undercooled liquid alloys at 682°C

Fig. 8: Al-Li-Zn.Difference (in kJ@mol-1) between the experimental and the calculated enthalpy of mixing of Al-Li-Zn ternary liquid and undercooled liquid alloys at 682°C using the association model