Acta Materialia 51 (2003) 2319–2330www.actamat-journals.com

Thermodynamic predictions of wrought alloy compositionsamenable to semi-solid processing

A. Maciel Camachoa,1, H.V. Atkinsonb,∗, P. Kapranosb, B.B. Argentb

a Instituto Tecnologico de Morelia., Av. Tecnologico 1500, CP 58120 Morelia, Mich., Mexicob Department of Engineering Materials, University of Sheffield, Mappin Street, Sheffield S1 3JD, UK

Received 20 December 2002; accepted 8 January 2003

Abstract

Semi-Solid Metal (SSM) Processing or Thixoforming is now a commercially successful manufacturing route produc-ing millions of near net-shape parts per annum for the automotive industry. Currently, effort is directed towardsdeveloping wrought performance alloys that are amenable to the thixoforming process. Here, the 7000 series Al–Zn–Mg–Cu system has been studied by means of thermodynamic modelling to identify those compositions likely to bemost suitable. The non-equilibrium solidification has been determined by using the Scheil equation and the liquidfraction/temperature relationship obtained. The results show the effect of chemical composition and Zn/Mg ratio onthe slope of the liquid fraction/temperature curves. As the Zn+ Mg + Cu content increases and the Zn/Mg ratiodecreases, the slopes of these curves become less steep. The effect of chemical composition, Zn/Mg ratio and tempera-ture on equilibrium phases is also considered. The phases in equilibrium at a given temperature are strongly affectedby the Zn/Mg ratio and Cu content. 2003 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.

Keywords: Aluminium alloys; Thermodynamics; Phase equilibria; Semi-solid processing

1. Introduction

Thixoforming—or semi-solid processing—is theshaping of metal components in the semi-solidstate. For this to be possible, the alloy must havean appreciable melting range and, before forming,

∗ Corresponding author. Nowat: Department of Engineering,University of Leicester, University Rd., Leicester LE1 7RH,UK. Fax: +44-116-2522-525.

E-mail address: hva2@le.ac.uk (H.V. Atkinson).1 Visiting Scientist in the Sheffield Thixoforming Group,

2000–1.

1359-6454/03/$30.00 2003 Acta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.doi:10.1016/S1359-6454(03)00040-5

the microstructure must consist of solid metalspheroids in a liquid matrix. In this state, the alloyis thixotropic: if it is sheared the viscosity falls andit flows like a liquid, but if allowed to stand itthickens again. Thus, a slug of alloy, heated intothe semi-solid state can be cut with a knife andspread like butter, provided the microstructure isnon-dendritic. This extraordinary behaviour wasfirst discovered at MIT [1] and has since led toextensive work on the thixotropy of alloy slurriesand the exploitation of the process. Fig. 1 showstypical thixoforming arrangements. The slug isgenerally heated in an induction heater until it

2320 A.M. Camacho et al. / Acta Materialia 51 (2003) 2319–2330

Fig. 1. Top: computer controlled hydraulic vertical thixoforming press, University of Sheffield, where semi-solid slug is heated insitu; and bottom: typical commercial hydraulic horizontal thixoforming press, where the semi-solid slug is transferred to the pressafter being induction heated on an external carousel.

reaches the required semi-solid state and then for-ced into the die by a ram. Slugs are usually orien-tated vertically during heating but there are somehorizontal arrangements where the slug is placed ina container to catch any escaping liquid. Horizontalheating arrangements tend to operate with liquidfractions around 0.6, vertical with 0.4.

Thixoforming is now widely used as a manufac-turing process that produces near net-shape metalcomponents for safety critical automotive appli-cations. There are several advantages over classical

die-casting [2–5]. The ranges of components pro-duced commercially are generally made from Al–Si casting alloys [5–7]. In the current state ofexpansion, attention is being paid to the possibilityof thixoforming aluminium alloys of higher mech-anical properties, which are generally wrought. Forexample, the 7000 series Al-alloys based on theAl–Zn–Mg–Cu quaternary system are extensivelyused in aircraft construction and other highstrength applications. These alloys achieve theirhigh strength by precipitation through a complex

2321A.M. Camacho et al. / Acta Materialia 51 (2003) 2319–2330

sequence of heat treatments and plastic defor-mation [8–12]. There are inherent difficulties inthixoforming these alloys though. The freezingranges are narrower and the fraction liquid tem-perature curves are steeper than for the standardAl–Si casting alloys [5]. Liquid fraction controlsto a large extent the rheological behaviour and theevolution of microstructure in the semisolid state[13,14]. Thus, this parameter is of critical impor-tance, both for fundamental work and for the con-trol of the industrial process. Therefore, it isimportant to evaluate a priori the evolution of theliquid fraction with temperature.

For successful assessment of existing alloys orthe development of new ones, thermodynamicmodelling techniques can be useful [15–20]. Thetheoretical basis for such modelling is well estab-lished (e.g. [21]). The aim of the present work wasto investigate quantitatively the effect of thealloying elements on the liquid fraction evolutionduring solidification and the phases in equilibriumin the Al–Zn–Mg–Cu system.

2. Method

The phases in equilibrium were determined byusing a commercial software package, MTDATArelease 4.72, developed by the National PhysicalLaboratory (NPL), NPL alloy solution databaseMTSOL v 1.1 and SGTE (Scientific Group Therm-odata Europe) substance database 9.0. Calculationsduring non-equilibrium have been made using theScheil simulation routine TSCHEIL, for multi-component systems, available with MTDATA. Thesystems treated have been Al–Zn–Mg, Al–Zn–Mg–Cu or multi-component commercial alloys. Inthe case of the Al–Zn–Mg system, the relevantparameters are known, but for the Al–Zn–Mg–Cusystem some of the interaction parameters are notavailable to describe the solution of copper in theC14 Laves phase h or the AlMgZn t phase. In con-sidering the commercial alloys, it is important torecognise that, in most cases, with eight compo-nents, it is highly unlikely that the thermodynamicdata necessary for a full treatment will be avail-able. In some cases, ternary phases, e.g.Al18Cr2Mg3 are missing. In other cases, unary data

that would permit the consideration of the solutionin a compound such as Al13Fe4, are only availablefor a limited number of elements—in this case Siand Mn. In many more cases, binary interactionparameters are missing—amounting to many hun-dreds of terms, although, in practice, only a limitednumber of these are likely to be important whenonly limited concentration ranges are considered.Nevertheless, for the C14 Laves phase, which isimportant in the 7000 series of alloys, a significantnumber of binary interaction terms are missing.Where interaction parameters are missing, idealsolutions were assumed.

“Scheil type” conditions have been assumed.The justification for this is that during thixoform-ing, reheating into the semi-solid state takes placerapidly (e.g. ~2 min overall in the Sheffield rig) byinduction heating. There is, therefore, insufficienttime for equilibrium to be established.

3. Results and discussion

3.1. Liquid fraction sensitivity

The liquid fraction sensitivity, (dfL /dT), definedas the rate of change of the liquid fraction (fL) withtemperature [22,23], is a very important parameterfor semi-solid forming; it can be obtained exper-imentally by differential scanning calorimetry(DSC) and predicted by thermodynamic modelling.Using DSC, it is necessary to prepare the alloys inorder to be able to have samples. This wouldinvolve a long experimentation time to analyse asystem like Al–Zn–Mg–Cu. Thermodynamic mod-elling allows the investigation of liquid fractionsensitivity to proceed without the need to prepareany material.

The aluminium alloy 7000 series can be dividedinto two main groups [8]: medium strength weld-able (Al–Zn–Mg) and high strength non-weldable(Al–Zn–Mg–Cu). The first group has very little orno Cu. In the first group, the effect of Zn/Mg ratioand the Zn + Mg content on the liquid fractionsensitivity were analysed and in the second groupthe effect of Zn/ (Mg + Cu) ratio and the Zn +Mg + Cu content. For convenience and compati-bility with past work, weight percentages are used

2322 A.M. Camacho et al. / Acta Materialia 51 (2003) 2319–2330

Fig. 2. Effect of the Zn/Mg ratio on the liquid fraction (Schielequation).

in describing and discussing the compositions usedin the Scheil calculations but mole fractions or at%are used in discussing sensitivities and the equilib-rium calculations. In Figs. 2–5 all ratios and sumsare in wt%.

Figs. 2 and 3 show the calculations of the liquidfraction/temperature relationship using an analyti-cal solution based on Scheil’s equation for multi-

Fig. 3. Effect of the sum of Mg + Zn on liquid fraction (Scheilequation).

Fig. 4. Effect of the Zn/ (Mg + Cu) ratio on the liquid fraction(Scheil equation).

Fig. 5. Effect of the (Zn + Mg + Cu) content on liquid fraction(Scheil equation).

component systems. Fig. 2 presents the calcu-lations for three alloys with different Zn/Mg ratios,keeping constant the sum Zn + Mg = 6 wt%. Fromthe graph it is possible to see that the slopes of thecurves at liquid fraction=0.4,(dfL /dT)fL = 0.4,become less steep as the Zn/Mg ratio decreases, inother words the sensitivity is reduced. Fig. 3 showsthe calculations for four alloys with the sameZn/Mg ratio (i.e. 1.5) but different Zn + Mg con-

2323A.M. Camacho et al. / Acta Materialia 51 (2003) 2319–2330

tents. The sensitivity is lower as the Zn + Mg con-tent increases.

For the second group of alloys in the Al–Zn–Mg–Cu system, the liquid fraction/temperaturerelationship was calculated for various Zn / (Mg +Cu) ratios and Zn + Mg + Cu content. Fig. 4presents the effect of Zn/ (Mg + Cu) ratio on thesensitivity. As the ratio decreases, the slopebecomes less steep. To be specific, when the Zn/(Mg + Cu) ratios are 1.25, 2 and 5 and the Zn +Mg + Cu content is constant and equal to 9 wt%,the sensitivities are 0.011, 0.013 and 0.018 molefraction °C�1, respectively. Fig. 5 shows the effectof the Zn + Mg + Cu content on the sensitivity. Inthis case, four commercial alloys and a model alloywere analysed, (7001, 7010, 7116, 7005 and ModelA). Their Zn + Mg + Cu contents are 12.5, 10.3,6.7, 6.0 and 12 wt%, respectively. Four of thealloys have the same Zn/ (Mg + Cu) ratio equal to1.5, whilst 7005 has a Zn/ (Mg + Cu) ratio of 3.As can be seen from the graph, the sensitivitydecreases as the Zn + Mg + Cu increases. In Table1, the results for both groups are summarised. Thealloy compositions are given in wt% with at% inbrackets.

The selection of the more suitable liquid fractionfor SSM processing depends on several factors, forexample: the orientation of the slug in the heatingchamber (vertical or horizontal); theheight/diameter ratio for the slug (squatter slugsare less susceptible to slumping in verticalarrangements); the shape and size of the part (morecomplex, larger parts require higher liquidfractions). In addition, the higher the liquid frac-tion, the higher the energy consumption. On theother hand, the resistance to hot tearing is usuallyrelated in aluminium alloys to a wide solidificationtemperature range. A definite advantage of semi-solid forming is that limiting the liquid fraction inthe semisolid can control both the solidificationrange and the shrinkage [24,25]. All these factorsmust be considered in selecting the bestliquid/solid ratio. Most authors [7,26–30] agreethat the liquid fraction must be in the range 0.3–0.5. A criterion can then be defined to qualify alu-minium alloys as suitable or non-suitable for thix-oforming. The criterion chosen here is the liquidfraction sensitivity to temperature change at a

liquid fraction of 0.4, (dfL /dT)fL = 0.4, 0.4 being themid-point of the range 0.3–0.5.

The sensitivity value should be as low as poss-ible. Heating is dynamic with temperature hetero-geneity through the slug. If the sensitivity is high,parts of the slug may have developed too muchliquid whilst other parts still have not reached anadequate value for processing conditions. The alloyA356 that has been extensively shaped by thix-oforming can be taken as a point of reference. Ithas a sensitivity value of 0.011 mole fraction °C�1

and the temperature range between 30 and 50% ofliquid, �T0.3/0.5, is around 18 °C.

The commercial weldable aluminium alloyswith Zn/Mg � 2 (in wt% terms) and Zn + Mg� 6 wt%, and consequently high sensitivities(Table 1), are not promising candidates for thix-oforming. In order to reduce the sensitivity, it isnecessary to increase the Zn + Mg content (�7wt%) and/or decrease the Zn/Mg ratio (�2). How-ever, these two parameters are very important inthe design of aluminium alloys because they con-trol the mechanical strength, corrosion resistanceand weldability. As Zn + Mg content is raised, ten-sile strength increases, but the resistance to stresscorrosion cracking (SCC) decreases. The Zn +Mg should be less than 6 wt% and Zn/Mg ratio inthe range of 2.7–2.9 to maximise the resistance toSCC [8].

In the second group of high strength non-weld-able alloys, based on the quaternary A–Zn–Mg–Cu, the resistance to SCC is improved with theaddition of Cu and, as a result, the Zn + Mg contentcan be higher than 6 wt%. For instance, in the alloy7001, Zn + Mg is 10.4 wt%. Another effect of theCu is that it increases the melting range and hencelowers the sensitivity. Analysing the values inTable 2, it can be seen that alloys 7001 and 7010with sensitivities equal to 0.009 and 0.011 molefraction °C�1 are promising candidate alloys forSSM processing. In contrast, the alloy 7005 witha higher sensitivity value (0.019 °C�1) and a low�T0.3/0.5 of 11 °C is not a promising candidate forSSM processing.

3.2. Phase precipitation

The sensitivity and the �T0.3/0.5 are not the onlyfactors to be considered in deciding which alloys

2324 A.M. Camacho et al. / Acta Materialia 51 (2003) 2319–2330

Table 1Sensitivity (S in mole fraction/°C) and temperature range for Al-alloys for 0.3–0.5 liquid fraction �T0.3/0.5 (°C). Compositions are inw% with a% figures given in brackets. Balance is Al

(a) Medium strength weldable alloys

Zn wt% Mg wt% Zn/Mg wt% Zn+Mg wt% S mole �T0.3/0.5 °C(at%) (at%) (at%) (at%) fraction/°C

5.14 (2.18) 0.86 (0.97) 1.00 (2.25) 6.0 (3.15) 0.017 11.74.20 (1.77) 1.80 (2.05) 2.33 (0.86) 6.0 (3.82) 0.022 9.05.00 (2.11) 1.00 (1.14) 5.00 (1.85) 6.0 (3.25) 0.033 6.03.00 (1.27) 2.00 (2.27) 1.50 (0.55) 5.0 (3.54) 0.023 8.73.60 (1.51) 2.40 (2.73) 1.50 (0.55) 6.0 (4.24) 0.018 10.74.80 (1.98) 3.20 (0.35) 1.50 (5.66) 8.0 (2.33) 0.013 15.76.00 (2.46) 4.00 (4.41) 1.50 (0.56) 10.0 (6.87) 0.010 20.0

(b) High strength non-weldable alloys

Zn wt% Mg+Cu Zn/Mg+Cu wt% Zn+Mg+Cu wt% S mole �T0.3/0.5 °C Commentwt% fraction/°C

5.00 4.00 1.25 9.00 0.0111 18.0 7022=4.75 wt% Zn, 3.85 wt%Mg+Cu

6.00 3.00 2.00 9.00 0.0125 16.07.50 1.50 5.00 9.00 0.0182 11.0 7076 same Zn, more Mg+Cu4.02 2.68 1.50 6.70 0.0200 10.06.18 4.12 1.50 10.30 0.0111 18.0 Simplified 70106.45 4.3 1.50 10.75 0.0100 20.07.50 5.00 1.50 12.50 0.0080 25.0 Simplified 7001

are likely to be most suitable for thixoforming. Thepossible phases in equilibrium must also be takeninto account, because the phases are directlyresponsible for the mechanical properties. In thecase of the Al–Zn–Mg–Cu quaternary system, age-ing is a complex process that involves principallythree phases, C14 Laves phase η(MgZn2), τphase—with variable Al, Mg, Zn and Cu (basedon AlMgZn in the Al–Mg–Zn system but alsofound in the Al–Cu–Mg system and modelled as(Mg)26(Al,Mg)6(Al,Cu,Mg)48(Al) by Bu�hler [31])and S(Al2CuMg). The precipitation and amount ofeach phase depend on the alloy composition and,in particular, the Zn/Mg ratio, which is consideredmost critical in determining which type of precipi-tation reaction takes place.

Fig. 6a–g show a set of calculations for commer-cial 7000 series high strength aluminium alloys toobserve how the calculated phases in equilibriumvary as the composition of the alloy changes. The

chemical compositions and Zn/Mg ratios are givenin Table 2 and the figures follow the order in Table2, i.e. the alloy with the highest Zn/Mg ratio (inat% terms) is first and the others follow indescending Zn/Mg ratio value. The table showswt% figures in brackets so that direct comparisonscan be made with Table 1. The figures show theprecipitation of the three major hardening phases(η, S and τ) and also Al13Fe4, Mg2Si, Al6Mn andAlCu—theta (Al2Cu). For the sake of clarity,phases with very low mole fractions are not shown.

As an aid to the discussion, ternary phase dia-gram sections at 400 K were calculated for Al–Cu–Mg, Al–Cu–Zn and Al–Mg–Zn using the TER-NARY module of MTDATA and MTSOL (Figs.7–9). From the Al–Mg–Zn diagram, Fig. 9, onecan see that at low Mg levels the C14 Laves phaseis expected and that at higher levels one may alsoexpect the τ phase. Alloys 7076 and 7005 have lowCu and Mg levels and show the Laves phase but

2325A.M. Camacho et al. / Acta Materialia 51 (2003) 2319–2330

Tab

le2

Com

mer

cial

allo

yco

mpo

sitio

nsin

a%(w

ithw

%in

brac

kets

),Z

n/M

gan

dC

u/M

gR

atio

s,to

tal

Zn

+M

g+

Cu

cont

ent,

sens

itivi

ty(S

inm

ole

frac

tion/

°C)

and

tem

pera

ture

rang

efo

r0.

3–0.

5liq

uid

frac

tion

(�T0

.3/0

.5in

°C)

Allo

ySi

at%

Feat

%C

uat

%M

nat

%M

gat

%Z

nat

%C

rat

%(w

t%)

Zn/

Mg

at%

Cu/

Mg

at%

Zn+

Mg+

Cu

S�

T(w

t%)

(wt%

)(w

t%)

(wt%

)(w

t%)

(wt%

)(w

t%)

(wt%

)at

%(w

t%)

0.3

/0.5

7076

0.42

(0.4

1)0.

31(0

.60)

0.31

(0.7

0)0.

26(0

.50)

1.87

(1.6

0)3.

27(7

.50)

–1.

74(4

.68)

0.17

(0.4

3)5.

45(9

.80)

––

7005

0.35

(0.3

5)0.

20(0

.40)

0.04

(0.1

0)0.

28(0

.55)

1.6

(1.5

0)1.

92(4

.50)

0.09

(0.1

6)1.

2(3

.21)

0.03

(0.0

7)3.

56(6

.00)

0.01

911

7010

0.12

(0.1

2)0.

08(0

.15)

0.78

(1.7

5)0.

05(0

.10)

2.67

(2.3

0)2.

68(6

.20)

0.03

(0.0

5)1.

00(2

.70)

0.29

(0.7

6)6.

13(1

0.25

)0.

011

1970

010.

36(0

.35)

0.20

(0.4

0)0.

95(2

.10)

0.10

(0.2

0)3.

53(3

.00)

3.24

(7.4

0)0.

14(0

.25)

0.92

(2.4

6)0.

27(0

.70)

7.71

(12.

50)

0.00

926

7075

0.40

(0.4

0)0.

25(0

.50)

0.71

(1.6

0)0.

15(0

.30)

2.90

(2.5

0)2.

42(5

.60)

0.12

(0.2

3)0.

83(2

.24)

0.24

(0.6

4)6.

04(9

.70)

––

Mod

elA

0.12

(0.1

2)0.

05(0

.10)

0.89

(2.0

0)0.

00(0

.00)

4.64

(4.0

0)2.

59(6

.00)

0.01

(0.0

2)0.

56(1

.50)

0.19

(0.5

0)8.

11(1

2.00

)0.

008

2970

220.

50(0

.50)

0.25

(0.5

0)0.

31(0

.70)

0.15

(0.3

0)3.

62(3

.15)

2.03

(4.7

5)0.

11(0

.20)

0.56

(1.5

0)0.

09(0

.22)

5.95

(8.6

0)–

–

2326 A.M. Camacho et al. / Acta Materialia 51 (2003) 2319–2330

Fig. 6. Calculated mole fraction of phases vs temperature plots for aluminium alloys: (a) 7076, (b) 7005, (c) 7010, (d) 7001, (e)7075, (f) Model A (AlZn6Mg4Cu2) and (g) 7022.

2327A.M. Camacho et al. / Acta Materialia 51 (2003) 2319–2330

Fig. 7. Calculated phase diagram for Al–Cu–Mg at 400 K.

Fig. 8. Calculated phase diagram for Al–Cu–Zn at 400 K.

2328 A.M. Camacho et al. / Acta Materialia 51 (2003) 2319–2330

Fig. 9. Calculated phase diagram for Al–Mg—Zn at 400 K.

not the tau phase. However, alloy 7022 whilst hav-ing a low Cu content, has relatively high Mg andZn and shows both the Laves and tau phases.Alloys 7001 and 7010 both show tau over a limitedtemperature range but this disappears below 600 Kas the C14 Laves phase appears.

None of the alloys have Mg contents sufficientlyhigh to meet the stoichiometric requirement for theLaves phase of xZn /xMg = 2 for their zinc contents.Therefore, the amount of Laves phase is to a largeextent determined by the Zn content with alloys7076 and 7001 showing the highest levels andalloys 7005 and 7022 showing the lowest levels.

From the ternary diagrams for Al–Cu–Mg andAl–Cu–Zn (Figs. 7 and 8), it can be seen that atlow Cu levels the AlCu—theta phase will be foundprovided the Mg levels are not too great. Thus,alloys 7076 and 7005 show the AlCu—theta phasebut not alloy 7022. Calculations with an MTDATAapplication TRISECT for a section through the Al–Cu–Mg–Zn system at 0.8 at% Cu and 400 K con-firmed the expectation that the presence of zincwould favour the formation of the C14 Laves phasebased on MgZn2 and thus for 2 at% Zn one should

expect that 1 at% of Mg more would be requiredto inhibit the formation of AlCu—theta than in theabsence of zinc.

As would be expected from the Al–Cu–Mg dia-gram (Fig. 7), the S phase becomes important athigher levels of Cu, joining with the Laves phasein supplanting the tau phase in alloys 7001 and7010, and competing with the tau phase over a lim-ited temperature range for alloys A and 7022. Thedecline in the amount of S phase in these alloys isassociated with the precipitation of the C14 Lavesphase and reflects the demands made by this phasefor Mg.

The percentages of Mg2Si, Al6Mn and Al13Fe4

depend on the Si, Mn and Fe contents, respect-ively, but also on the other phases so there is nosimple correlation.

Overall, the Zn/Mg ratio is an important para-meter in the Al–Zn–Mg–Cu alloys. It affects theequilibrium phases (and consequently the mechan-ical properties), the resistance to SCC and theliquid fraction sensitivity.

2329A.M. Camacho et al. / Acta Materialia 51 (2003) 2319–2330

4. Conclusions

Thermodynamic modelling is a useful tool in thefirst stage of designing new alloys for thixoform-ing.

1. Thixoformability should increase as the Zn/Mgratio decreases and the sum Zn + Mg + Cuincreases.

2. The optimum conditions for thixoformingshould be obtained when Zn/Mg � 2.5 (in wt%terms) and Zn + Mg + Cu � 7wt%.

3. Alloys with Zn + Mg + Cu content less than 7wt% will be difficult to thixoform, even at verylow Zn/Mg ratios.

4. The Zn/Mg ratio is an important parameterinfluencing the equilibrium phases (and conse-quently the mechanical properties and stresscorrosion cracking) and thixoformability. Alloys7075 and 7010 have all three hardening phasesη, S and τ present at room temperature. Forthese alloys, Cu is higher than 0.7 at%, and theZn/Mg ratio is intermediate (0.83 and 1.0,respectively, in at% terms).

Acknowledgements

AMC is grateful to the Mexican Council forScience and Technology (CONACYT) for support-ing this research with a sabbatical scholarship. PKis grateful to the Engineering and PhysicalSciences Research Council for support under GrantNo. GR/M 89096 “Alloy Development for Thix-oforming” .

References

[1] Spencer DP, Mehrabian R, Flemings MC. Metall Trans1972;3:1925–32.

[2] Flemings MC. In: Chiarmetta G, Rosso M, editors. Proc.6th Int. Conf. on Semi-Solid Processing of Alloys andComposites; Turin, Italy; 2000 Sep 27–29. Brescia, Italy:Edimet-Spa; 2000. p. 11–3.

[3] Chiarmetta G. In: Chiarmetta G, Rosso M, editors. Proc.6th Int. Conf. on Semi-Solid Processing of Alloys andComposites; Turin, Italy; Sep 27–29. Brescia, Italy: Edi-met-Spa; 2000. p. 15–21.

[4] Young K, Eisen P. In: Chiarmetta G, Rosso M, editors.Proc. 6th Int. Conf. on Semi-Solid Processing of Alloysand Composites; Turin, Italy; Sep 27–29. Brescia, Italy:Edimet-Spa; 2000. p. 97–102.

[5] Atkinson HV, Kapranos P, Kirkwood DH. In: ChiarmettaG, Rosso M, editors. Proc. 6th Int. Conf. on Semi-SolidProcessing of Alloys and Composites; Turin, Italy; Sep27–29. Brescia, Italy: Edimet-Spa; 2000. p. 443–50.

[6] Kapranos P, Ward PJ, Atkinson HV, Kirkwood DH. MaterDesign 2000;21:387–94.

[7] Winterbottom WL. In: Chiarmetta G, Rosso M, editors.Proc. 6th Int. Conf. on Semi-Solid Processing of Alloysand Composites; Turin, Italy; Sep 27–29. Brescia, Italy:Edimet-Spa; 2000. p. 73–8.

[8] Polmear IJ. Light alloys: metallurgy of the light metals,3rd ed. London: Arnold, 1995.

[9] Dons AE, Jensen EK, Langsrud Y, Trømborg E, Bruse-thaug S. Metall Mater Trans A 1999;30A:2135–46.

[10] Deschamps A, Brechet Y, Livet F. Mater. Sci. Technol.1999;15:993–8.

[11] Ludtka GM, Laughlin DE. Metall Trans A1981;12A:2087–91.

[12] Maloney SK, Hono K, Polmear IJ, Ringer SP. Scriptamater 1999;41(10):1031–8.

[13] Kirkwood DH. Int Mater Rev 1994;39(5):173–89.[14] Tzimas E, Zavaliangos A. In: Froes FH, Ward-Close CM,

McCormick PG, Eleizer D, editors. Synthesis of light-weight metals III, Proc. Conf. 1999 TMS Annual Meeting;San Diego; Feb 28–Mar 4. Warrendale, PA: TMS; 1999.p. 195–203.

[15] Kolby P. Aluminium alloys, Driver JH, Dubost B, editors.Mater Sci Forum 1996;217-222:661–6.

[16] Howe A, Farrugia DCJ. Mater Sci Technol 1999;15:15–20.

[17] Seifert HJ, Liang P, Lukas HL, Aldinger F, Fries SG, Har-melin MG et al. Mater Sci Technol 2000;16:1429–33.

[18] Kazakov AA. Adv Mater Processes 2000;157(3):31–4.[19] Apelian D. In: Chiarmetta G, Rosso M, editors. Proc. 6th

Int. Conf. on Semi-Solid Processing of Alloys and Com-posites; Turin, Italy; Sep 27–29. Brescia, Italy: Edimet-Spa; 2000. p. 47–54.

[20] Kaufman H, Wabusseg H, Uggowitzer PJ. In: ChiarmettaG, Rosso M, editors. Proc. 6th Int. Conf. on Semi-SolidProcessing of Alloys and Composites; Turin, Italy; Sep27–29. Brescia, Italy: Edimet-Spa; 2000. p. 457–62.

[21] Saunders N, Miodownik AP. CALPHAD (Calculation ofPhase Diagrams) a comprehensive guide. PergamonMaterials Series. UK: Elsevier Ltd, 1998.

[22] Tzimas E, Zavaliangos A. J Mater Sci 2000;35:5319–29.[23] Zavaliangos A, Lin JC, Yin M. In: Chiarmetta G, Rosso

M, editors. Proc. 6th Int. Conf. on Semi-Solid Processingof Alloys and Composites; Turin, Italy; Sep 27–-29. Bres-cia, Italy: Edimet-Spa; 2000. p. 463–8.

[24] Campbell J. Castings. Oxford, UK: Butterworth-Heine-man, 1991.

[25] Rappaz M, Drezet JM, Gremaud M. Metall Mater TransA 1999;30A(2):449–55.

2330 A.M. Camacho et al. / Acta Materialia 51 (2003) 2319–2330

[26] Farup I, Mo A. In: Proc. Conf. “Solidification and Grav-ity” , 2000, 329-3, 377–382.

[27] Mehrabian R, Flemings MC. Trans. AFS 1972;80:173–182, Die Casting Engineer (Jul–Aug 1973).

[28] Noll TR, Kiehne CH, Kruger J, Friedrich B. In: Chiar-metta G, Rosso M, editors. Proc. 6th Int. Conf. on Semi-Solid Processing of Alloys and Composites; Turin, Italy;Sep 27–29. Brescia, Italy: Edimet-Spa; 2000. p. 35–40.

[29] Eisen P, Young K. In: Chiarmetta G, Rosso M, editors.Proc. 6th Int. Conf. on Semi-Solid Processing of Alloysand Composites; Turin, Italy; Sep 27–29. Brescia, Italy:Edimet-Spa; 2000. p. 41–6.

[30] Wang L, Makhlouf M, Apelian D. Int Mat Rev1995;40(6):221–38.

[31] Bu�hler T. RWTH, Germany. In: Ansara I, Dinsdale AT,Rand MH, editors. COST 507 Definition of thermochem-ical and thermophysical properties to provide a databasefor the development of new light alloys “Thermochemicaldatabase for light metal alloys, vol 2, EUR 18499 EN,ISBN 92-828-3900-1. Luxembourg: Office for OfficialPublications of the European Communities; 1998. p. 92–828.

本文献由“学霸图书馆-文献云下载”收集自网络，仅供学习交流使用。

学霸图书馆（www.xuebalib.com）是一个“整合众多图书馆数据库资源，

提供一站式文献检索和下载服务”的24 小时在线不限IP

图书馆。

图书馆致力于便利、促进学习与科研，提供最强文献下载服务。

图书馆导航：

图书馆首页 文献云下载 图书馆入口 外文数据库大全 疑难文献辅助工具