O71-Thermodynamic Analysis for the Mg-Zn-Zr and the Mg-Zn-Ca …paginas.fe.up.pt/~tofa2010/Apresentacoes_TOFA2010/O71... · 2010-11-03 · 50,000,000 vehicles/year ××××20 kg/vehicle

2010-TOFA

Thermodynamic Analysis for

the Mg-Zn-Zr and the Mg-Zn-Ca Alloysthe Mg-Zn-Zr and the Mg-Zn-Ca Alloys

Changrong Li, Qiuci Zhao, Cuiping guo, Zhenmin Du

School of Materials Science and Engineering

University of Science and Technology Beijing

50,000,000 vehicles/year20 kg/vehicle ××××

Mg Alloys

32%

Alloying element of Al Alloys

43%

Others

25%

Global Mg consumptions

of automobile market

Thermodynamic Analysis for the Mg-Zn-Zr and the Mg- Zn-Ca Alloys

2

1,000,000,000 kg/yearGlobal Mg consumptions

in 2004

Thermodynamic Analysis for the Mg-Zn-Zr and the Mg- Zn-Ca Alloys

Preface to “Mg and Mg alloys”

Wenxian Li, “Mg and Mg Alloys”,

Central South University Press, Changsha, 2005.

3

In the materials field, there is no other materials than

Mg alloys, showing so big difference between the

development potential and the actual applications.

Assessments for Mg thermodynamic database

Thermodynamic analysis for Mg-Zn-Zr alloys

Thermodynamic analysis for Mg -Zn-Ca alloys

2

3

Outlines

1

4

Thermodynamic analysis for Mg -Zn-Ca alloys

Further analysis on Mg-Zn-Ca-Zr alloys

Conclusions

3

4

5

Assessments for Mg thermodynamic database1

5

1. Assessments for Mg thermodynamic database

Size difference and solubilities of elements in Mg

possible

6Wenxian Li, “Mg and Mg Alloys”, Central South University Press, Changsha, 2005.

highsolubilities


Darken-Gurry rules and solubilities of elements in Mg

possiblehigh

solubilities

7Wenxian Li, “Mg and Mg Alloys”, Central South University Press, Changsha, 2005.

solubilities


Phase equilibria and solubilities of elements in Mg

8


The current status of Mg-based

phase diagrams can not meet

the demands of research and

development.79

7478

71

87

61

40

60

80

100Binaries

With Ph DWithout Ph D

60Total

Mg-Al-X Ternaries

Fe-X, Al-X and Mg-X Binaries

9Shiming Hao, J. Materials and Metallurgy, 2002, Vol.1, No.3, pp166-170

5 7

26

0

20

40

Fe-X Al-X Mg-X

51

1517 19

0

10

20

30

40

50

60

Tot alTot alTot alTot al Mor eMor eMor eMor eI nfI nfI nfI nf

LessLessLessLessI nfI nfI nfI nf

Wi t houtWi t houtWi t houtWi t houtPh DPh DPh DPh D

Total

More Inf

Less Inf

Without Ph D

Compared with Fe-based steels

and Al-based alloys, the phase

diagrams for Mg-based alloys

are far not enough.

LiLi LiLi

AlAl ** AlAl

SiSi ** ** SiSi

CaCa ** ** ** CaCa

ScSc nn ** nn nn ScSc

MnMn ** ** nn nn ** MnMn

CuCu ** ** ** oo nn nn CuCu

ZnZn ** ** ff ** nn ff ** ZnZn

YY ff ** ** nn ** ** ** ** YY

ZrZr ff ** nn ** nn ** nn nn ** ZrZr

Mg-X-Y ternary phase diagram status

��: optimized

o: obtainable diagram exper. infor.

p: partial diagram exper. infor,

f: few diagram exper. infor.Mg-Zn-Zr


10R Schmid-Fetzer. The 12th National Symposium on Phase Diagram, Materials Design and its Applications October 24~28, 2004, Shenzhen University, China

ZrZr ff ** nn ** nn ** nn nn ** ZrZr

NdNd nn ff nn nn nn nn nn pp ** nn NdNd

GdGd ** ** nn nn ** ** nn nn ** nn nn GdGd

AgAg oo pp nn nn nn nn pp pp nn nn ff nn AgAg

DyDy nn ** nn nn nn nn nn nn nn nn nn nn nn DyDy

CeCe ** ** ff nn ** ** nn pp ** nn nn nn ff nn CeCe

LaLa ff oo nn nn nn nn nn pp ff nn nn nn ff nn ff LaLa

SmSm nn ** nn nn nn nn nn pp pp nn nn nn ff nn nn nn SmSm

SbSb nn ff oo nn nn nn oo nn nn nn nn nn pp nn nn nn nn SbSb

SnSn pp pp ff nn nn ff pp pp nn nn nn nn oo nn nn nn nn oo SnSn

BiBi nn oo nn oo nn nn oo pp nn nn nn nn nn nn nn nn nn pp oo BiBi

SrSr nn pp nn ** nn nn nn nn nn nn nn nn nn nn nn nn nn nn nn nn SrSr

f: few diagram exper. infor.

n: no diagram exper. infor.Mg-Zn-Zr

Mg-Zn-Gd


Mg-Ce Mg-Nd Mg-Sm Mg-Pr Ag-Ca Al-Er

Ag-Nd Al-Fe Al -Mo Al-Sm Cu-Dy Ce-La

Thermodynamic assessments for Mg-based database

Optimized binary systems

11

Ag-Nd Al-Fe Al -Mo Al-Sm Cu-Dy Ce-La

Ce-Y Cr-Ge Dy-Zn Er-Zn Fe-Sb Gd-Sm

Gd-Zn Ho-Zn La-Ni La-Si La-Zn Mo-Si

Nb-Si Nd-Y Nd-Zn Pr-Y Pr-Zn Sm-Zn

Tb-Zn Th-Zn Yb-Zn

Journal Conference New

from University of Science and Technology Beijing, North-Eastern University and Central-South University


Thermodynamic assessments for Mg-based database

Optimized ternary systems

Mg-Ag-Ca Mg-Al-Ca Mg-Gd-Nd Mg-La-Ce Mg-Y-Al Mg-Zn-Ce

Mg-Ag-Nd Mg-Al-Mn Mg-Gd-Sm Mg-La-Ni Mg-Y-Ce Mg-Zn-Gd

Mg-Al -Sm Mg-Gd-Zn Mg-La-Si Mg-Y-Nd Mg-Zn-La

12

Journal Conference New

from University of Science and Technology Beijing, North-Eastern University and Central-South University

Mg-Al -Sm Mg-Gd-Zn Mg-La-Si Mg-Y-Nd Mg-Zn-La

Mg-Al-Y Mg-La-Zn Mg-Y-Sn Mg-Zn-Nd

Mg-Y-Zr Mg-Zn-Ni

Al-Sb-Y Al-Cu-Er Co-Ni-Sb Mg-Y-Pr Mg-Zn-Pr

Al-Fe-Mo Al-Li-Zn Cu-Nb-Sn Mg-Zn-Sm

Thermodynamic analysis for Mg-Zn-Zr alloys2

13

Zr: a=0.323nm, c=0.514nm

Crystalline structure

2. Thermodynamic analysis for Mg-Zn-Zr alloys

Zr is an effective grain refiner

Phase equilibrium

Zr: a=0.323nm, c=0.514nm

Mg: a=0.321nm, c=0.521nm

14


Three constituent binaries of the Mg-Zn-Zr ternary

15

MgMg--Zn binaryZn binary Mg-Zr binary Zn-Zr binary


Liquidus surface projection of the Mg-Zn-Zr ternary

16

Comparison of the liquidus surface projection Comparison of the liquidus surface projection between the calculated results (a) and the experime ntal data (b)between the calculated results (a) and the experime ntal data (b)


Thermodynamic study on the Zr grain-refiner

17

�� With more Zr content, the liquidus line goes upWith more Zr content, the liquidus line goes up. The potential undercooling . The potential undercooling degree increases, which is favorable to grain size refining.degree increases, which is favorable to grain size refining.

�� When Zr content is too high, the primary crystalline phase will be bccWhen Zr content is too high, the primary crystalline phase will be bcc--Zr, which Zr, which is not suitable to be used as the substrate of heterogeneous nucleation. is not suitable to be used as the substrate of heterogeneous nucleation.

�� The optimum Zr content is from 0.6 to 1.o wt.%.The optimum Zr content is from 0.6 to 1.o wt.%.

Zn=2 wt% Zn=6 wt%Zn=4 wt%



18

�� With more Zn content, the liquidus line goes down. The potential undercooling With more Zn content, the liquidus line goes down. The potential undercooling degree decreases, which is not favorable to grain size refining.degree decreases, which is not favorable to grain size refining.

�� When Zr content is not high enough, the Zn content can not be too high.When Zr content is not high enough, the Zn content can not be too high.

Zr=0.6 wt% Zr=1.0 wt%



BrandBrandComposition, wt.%Composition, wt.%

MgMg ZnZn ZrZr CuCu NiNi othersothers

ZK51AZK51A balancebalance 3.83.8～～～～～～～～5.35.3 0.30.3～～～～～～～～1.01.0 ≤0.03≤0.03 0.0100.010 ≤0.3≤0.3

ZK61AZK61A balancebalance 5.75.7～～～～～～～～6.36.3 0.30.3～～～～～～～～1.01.0 ≤0.03≤0.03 ≤0.010≤0.010 ≤0.3≤0.3

19

ZK61AZK61A balancebalance 5.75.7～～～～～～～～6.36.3 0.30.3～～～～～～～～1.01.0 ≤0.03≤0.03 ≤0.010≤0.010 ≤0.3≤0.3

ZK21AZK21A balancebalance 2.02.0～～～～～～～～2.62.6 0.450.45～～～～～～～～0.80.8 0.100.10 0.010.01 ≤0.3≤0.3

ZK31(a)ZK31(a) balancebalance 2.52.5～～～～～～～～3.53.5 0.50.5～～～～～～～～1.01.0 0.0020.002

ZK40AZK40A balancebalance 3.53.5～～～～～～～～4.54.5 ≮≮≮≮≮≮≮≮0.450.45 0.100.10 0.010.01 ≤0.3≤0.3

ZK60AZK60A balancebalance 4.84.8～～～～～～～～6.26.2 ≮≮≮≮≮≮≮≮0.450.45 ≤0.3≤0.3

ZK61(b)ZK61(b) balancebalance 5.55.5～～～～～～～～6.56.5 0.60.6～～～～～～～～1.01.0 0.010.01

Thermodynamic analysis for Mg-Zn-Ca alloys3

20

3. Thermodynamic analysis for Mg-Zn-Ca alloys

Various grain refining agents of Mg-alloys

Agent Alloy Strengthening phase Property and mechanism

Ca Mg–Al (Mg,Al) 2CaReducing dendrites, increasing ductility, inhibiting growth

Ca Mg-Zn Mg 2Ca, Ca2Mg6Zn3Refining grain size, enhancing dispersion strengthening

Sr Mg–Al Al 3Mg13Sr, Al 4Sr Decreasing grain growth rate

Sb Mg ingot Haxagonal Mg 3Sb2Improving strength, increasing nucleation positions

Zr Mg–ZnNot soluble in Mg solution

Inhibiting grain growth, offering heterogeneous nuclei

C-containing AZ3Ultrafine uniformly dispersed Al 4C3 particles

Refining grain size, preventing from burning, purificationRefining grain size, increasing anti -

21

Mn Mg–Al —Refining grain size, increasing anti -corrosion and anti-creep abilities

Cd — Cd3Mg, CdMg, CdMg 3 Increasing ductility

Al–Ti–C Mg–Al AZ61 Al 4C3/TiC compositeRefining grain size, increasing anti-corrosion ability and mechanical property

Nd ZM5 α-Mg solid solutionIncreasing anti-corrosion ability and thermo-stability

MgCO3La2(CO3)3 AZ91D Al 4C3Dispersion strengthening, decreasing intervals between secondary dendrites

Ba AZ91 High melting point Al 4BaDispersion strengthening, increasing HT tensile strength and heat resistance

Si Mg–Al Mg 2SiRefining grain size, improving anti-creep ability

Re Mg–Al Al 11RE3Refining grain size, improving cast performance and HT/LT properties


Three constituent binaries of the Mg-Zn-Ca ternary

22

MgMg--Zn binaryZn binary Mg-Ca binary Ca-Zn binary


Liquidus surface projection of the Mg-Zn-Ca ternary

[2004Brubaker]

Journal of Alloys and Compounds

2004, 370: 114–122

23


Thermodynamic study on the Ca alloying

24

�� With more Ca content, the temperature difference between the liquidus and the With more Ca content, the temperature difference between the liquidus and the solidus lines increases, favorable to grain size refining. solidus lines increases, favorable to grain size refining.

�� When Zn content is low, the CaWhen Zn content is low, the Ca22MgMg66ZnZn33 compound precipitates at low compound precipitates at low temperature. The hcptemperature. The hcp--Mg+CaMg+Ca22MgMg66ZnZn33 twotwo--phase region expands with increasing phase region expands with increasing Zn content, from which, the MgZn phase precipitatres at low temperature, Zn content, from which, the MgZn phase precipitatres at low temperature, favorable to precipitation strengthening.favorable to precipitation strengthening.

Zn=1 wt% Zn=5 wt%Zn=3 wt%


Age hardening experiments of the Mg-Zn-Ca alloys

25

[Gao2005] 98Mg-1Ca-1Zn

200oC 2h Age hardening peak

[Jaidim2004] 92.5Mg-1.5Ca-6Zn

200oC 1h Age hardening peak

X. Gao et al. / Scripta Materialia 53 (2005) 1321–1326

P.M. Jardim et al. / Materials Science and Engineering A 381 (2004) 196–205


Thermodynamic study on the Ca alloying

26

Alloy: 98Mg-1Ca-1Zn

Precipitate: Ca2Mg6Zn3

Ca=1.0 wt% Ca=1.5 wt%

AlloyAlloyAlloyAlloyAlloyAlloyAlloyAlloy: 92.5Mg: 92.5Mg--1.5Ca1.5Ca--6Zn6Zn

Precipitate: Precipitate: Precipitate: Precipitate: Precipitate: Precipitate: Precipitate: Precipitate: MgZnMgZn

Further analysis on Mg-Zn-Ca-Zr alloys4

27

4. Further analysis on Mg-Zn-Ca-Zr alloys

28

Zn=1.0 wt%

�� With more Zr content, the liquidus line goes up and the potential undercooling With more Zr content, the liquidus line goes up and the potential undercooling degree increases as well, favorable to grain size refining.degree increases as well, favorable to grain size refining.

�� With more Ca content, the difference between the liquidus and the solidus lines With more Ca content, the difference between the liquidus and the solidus lines increases, also favorable to grain size refining.increases, also favorable to grain size refining.

4. Further analysis on Mg-Zn-Ca-Zr alloys

29

(Zn=1 wt%)

◆ [X. Gao et al 2005] Mg–1Zn–1Ca–0.6Zr alloy: After age hardening, the tensile strength and the creep resistance are increased.

◆ [Nie & Muddle 1997] Mg-1Zn-1Ca-xZr alloy: The grain size is refined. And the tensile strength and the ductility are increased.

Conclusions5

30

5. Conclusions

◆ In the Mg-Zn-Zr system, Zr is an effective grain refiner. When the Zr is low, the grain growth can be inhibited. When the Zr content is high, the heterogeneous nucleation is promoted.

◆ In the Mg-Zn-Ca system, Ca is an effective alloying element. More Ca content is favorable to grain size refining. And the precipitation of Mg-containing compounds can enhance the

31

precipitation of Mg-containing compounds can enhance the dispersion strengthening.

◆ The proper addition of both Zr and Ca alloying elements in the Mg-Zn alloys, the grain size refining effect may be more than doubled? The compound precipitation from the Mg-matrix may be favorable to the dispersion strengthening? The Mg-Zn-Ca-Zr quaternary is an important system and needs to be concerned.

2010中国材料大会湖南长沙

Documents

O71-Thermodynamic Analysis for the Mg-Zn-Zr and the Mg-Zn-Ca …paginas.fe.up.pt/~tofa2010/Apresentacoes_TOFA2010/O71... · 2010-11-03 · 50,000,000 vehicles/year ××××20 kg/vehicle