T. Huber and A. Mohammed CompTest2003, Châlons-en-Champagne Jan. 2003 Thermal Expansion Behaviour of Metal-Matrix Composites T. Huber, A. Mohammed and.

IMSTInstitute of Materials Science & Testing


T. Huber and A. MohammedCompTest2003, Châlons-en-Champagne Jan. 2003

Thermal Expansion Behaviour of Metal-Matrix Composites

T. Huber, A. Mohammed and H.P. Degischer

Vienna University of TechnologyInstitute of Materials Science & Testing, A-1040 Vienna/Austria




Part I

Thermal Expansion Behaviour of Particle Reinforced

Metal-Matrix Composites




Metal Matrix Composites Studied – Particle Reinforced

Material P2 (P1 is similar)

MaterialCode Matrix Reinforcement

Fabrication process Condition

P1 Al99.5SiCp; 70 vol.-% particle size:

3m to 80m gas pressure infiltration

as-cast

P2 AlSi7Mg(A356)

overaged

P3 AlSi7Mg(A356)

SiCp; 55 vol.-%particle size: ~80m

centrifugalcasting

overaged

P4 AlSi10Mg(A359)

SiCp; 20 vol.-%particle size: ~12m

stir casting/extruded

overaged

Material P3

Material P4




Thermal Mechanical Analysis (TMA)

moveable probe

sample

quartz stage

force: 0.1 NFurnace

moveable probe

sample

quartz stage

force: 0.1 NFurnace

TA Instruments® TMA 2940 (Wilmington, Delaware)

Percent Length Change (PLC)0L

ΔL0L

ΔL

Instantaneous Coefficientof Thermal Expansion (CTE) dT

dL

L(T)

1CTE(T) dT

dL

L(T)

1CTE(T)

Calculation range (from 20°C to 310°C)

10°C

320°C Temp.

Timeheating and cooling rate: 3 K/min10 minutes holding time

Calculation range (from 20°C to 310°C)

10°C

320°C Temp.

Timeheating and cooling rate: 3 K/min10 minutes holding time

(from 50°C to 490°C)

500°C

RT

Calculated parameters:




0 50 100 150 200 250 300 350 400 450 500 550-0,05

0,00

0,05

0,10

0,15

0,20

0,25

0,30

0,35

0,40

0,45

L/L

0 [%]

Temperature [°C]

1st Heating up - Al99.5 + 70 vol.% SiCp (material P1) 2nd Heating up - Al99.5 + 70 vol.% SiCp (material P1) 1st Heating up - AlSi7Mg + 70 vol.% SiCp (material P2) 2nd Heating up - AlSi7Mg + 70 vol.% SiCp (material P2)

Thermal Expansion Behaviour of AlSiC MMC

Section III

Section I

Section II • thermal behavior depends strongly on the reinforcement architecture• material P2: Si-bridges between SiC particles forming a percolating SiC-Si-network …• … prevent an accelerated thermal expansion

• linear to decreasing L/L0(T)

• internal stresses in the matrix surpass decreasing yield strength …• … relaxation processes (plastic flow, creep) occur• reduction in thermal expansion vanishing internal stresses• non linear increase of L/L0(T)

• with significant elastic straining• Young‘s modulus decreases with temperature




0 50 100 150 200 250 300 350 400 450 500 5504

5

6

7

8

9

10

11

12

13

14

Inst

anta

neou

s C

TE

[pp

m/K

]

Temperature [°C]

1st Heating up - Al99.5 + 70 vol.% SiCp (material P1) 2nd heating up - Al99.5 + 70 vol.% SiCp (material P1) 1st Heating up - AlSi7Mg + 70 vol.% SiCp (material P2) 2nd Heating up - AlSi7Mg + 70 vol.% SiCp (material P2)

Thermal Expansion Behavior of AlSiC MMC

Section II Section IIISection I

• non linear increase of L/L0(T)

increasing CTEs (slope of L/L0 curve)• significant elastic straining of the matrix

• linear to decreasing L/L0(T) CTE reaches a maximum and drops• thermal expansion is more and more dominated by the densely packed ceramic• simultaneously: closure of microvoids by local plastic flow of the matrix may occur

• material P2: Si-bridges between SiC particles forming a percolating SiC-Si-network …• … prevent an accelerated thermal expansion constant CTEs up to 500°C• material P1: matrix is continuously expanding (non percolating reinforcement) increasing CTE & voids being already filled with metal matrix




Microstructure of Al-SiC MMC – Material P2 (Section II & III)

• thermal behavior in section III depends strongly on the reinforcement architecture• material 1 & 3: Si-bridges between SiC particles forming a percolating SiC-Si-network …• … prevent an accelerated thermal expansion

SiC

SiCSiC

SiC

SiCSi

Si




Big SiC particles surrounded by small SiCparticles connected via “Si-bridges” fromthe matrix alloy.

Compact cluster of SiC particles connectedvia “Si-bridges”.

• after dendritic solidification of the matrix alloy (-phase) remaining eutectic liquid (12.6 mass-% Si) tends to freeze around the SiC particulates• ceramic particles do not act as preferential crystal nucleation sites• “Si-bridges” between SiC particles form a percolating “SiC-Si-network”

Microstructure of Al-SiC MMC – Material P2 (Section II & III)




Preexisting Microvoids – Material P2 (Section II & III)

voids

(a) SEM backscattered electron image (BEI)

(b) Image analysis – binary image of (a)(white area = voids)

Overlay of (a) and (b) average void volume fraction of an AlSiC MMC (result of 12 images)

1.3 0.5 vol.-%

Uncertainties of measurement:• broken SiC particles and removal of matrix alloy during metallographic preparation overestimation• closure of pores by smearing during metallographic preparation underestimation of porosity




0 50 100 150 200 250 300 350 400 450 500 55020

22

24

26

28

30

32 Al99.5 AlSi7Mg alloy - cast AlSi7Mg - cold rolled

Inst

an

tan

eo

us

CT

E [p

pm

/K]

Temperature [°C]

0 50 100 150 200 250 300 350 400 450 500 55020

22

24

26

28

30

32 Al99.5 AlSi7Mg alloy - cast

Inst

an

tan

eo

us

CT

E [p

pm

/K]

Temperature [°C]

0 50 100 150 200 250 300 350 400 450 500 55020

22

24

26

28

30

32 Al99.5

Inst

an

tan

eo

us

CT

E [p

pm

/K]

Temperature [°C]

Expansion Behaviour of the Matrix (Section II & III)

SEM micrograph of partially dissolved A356 alloy(removal of solid solution)showing the eutecticallysegregated Si-network

pure Al• increasing CTEs

A356 alloy - cast• similar behaviour as P1 and P2• percolating Si-network

A356 alloy – cold rolled• destroyed Si-network• no CTE drop down occurs




Expansion Behaviour of different Particle Reinforced MMCs

0 50 100 150 200 250 300 350 400 450 500 5502

4

6

8

10

12

20

22

24

26

28

30

32

Al99.5 AlSi7Mg alloy - cast Al99.5 + 70 vol.% SiCp (material P1) AlSi7Mg + 70 vol.% SiCp (material P2) AlSi7Mg + 55 vol.% SiCp (material P3) SiC-Si-network

Inst

anta

neou

s C

TE

[ppm

/K]

Temperature [°C]

Al99.5matrix

-phase(eutec.)

Si

AlSi7Mgor AlSi7matrix:

Material P1

Material P2

SiC

SiC -phase(eutec.)

Si

AlSi7Mgor AlSi7matrix:

Material P3




0 50 100 150 200 250 300 350 400 450 500 55012

14

16

18

20

22

24

26

28

30 AlSi10Mg alloy - extruded AlSi10Mg + 22 vol.% SiCp (material P4)In

stan

tane

ous

CT

E [p

pm/K

]

Temperature [°C]

Expansion Behaviour of an Extruded MMC

Extruded material• destroyed Si-network• no CTE drop down occurs




Solution treatment530°C / 6h

Quenched inwater

Slow coolingwith 3K/min

Temp.

TimeRT

Influence of Heat Treatments on the thermal behaviour – Material P2

Heat treatment400°C / 30 min

Quenched inwater




0 50 100 150 200 250 300 350 400 450 500 5504

6

8

10

12

14Material P2 - 1st Heating up

Solution HT/cooling(3K/min) to RT

Inst

anta

neou

s C

TE

[ppm

/K]

Temperature [°C]

0 50 100 150 200 250 300 350 400 450 500 5504

6

8

10

12


Inst

anta

neou

s C

TE

[ppm

/K]

Temperature [°C]

0 50 100 150 200 250 300 350 400 450 500 5504

6

8

10

12


Solution HT/cooling(3K/min) to RT Solution HT/quenched in water

Inst

anta

neou

s C

TE

[ppm

/K]

Temperature [°C]

0 50 100 150 200 250 300 350 400 450 500 5504

6

8

10

12


Solution HT/cooling(3K/min) to RT Solution HT/quenched in water 400°C for 30 min/quenched in water

Inst

anta

neou

s C

TE

[ppm

/K]

Temperature [°C]

„Peak“ within 1st heating up cycle Gradual formation of equilibrium phase Mg2Si precipitates (incoherent, overaged)in the A356 alloy, which causes a smalladditional volume change!

Influence of Heat Treatments on the thermal behaviour – Material P2

Coherent precipitate Incoherent precipitate0 50 100 150 200 250 300 350 400

-0,05

0,00

0,05

0,10

0,15

0,20

0,25

0,30

0,35

0,40

L/L

0 [%]

Temperature [°C]

1st Heating up 1st Cooling down 2nd Heating up

L

• Formation of incoherent Mg2Si precipitates 70% of L• Formation of incoherent Mg2Si precipitates 70% of L

• relief of internal stresses from quenching 30% of L




Conclusions – Particle Reinforced MMC CTE curves of P1 & P2 up to 500°C can be divided into three sections:

section I: matrix with significant elastic straining

section II: elastic straining decreases owing to decreasing yield strength of the matrix internal stresses can at least partly relax by local plastic flow

section III: behavior depends on reinforcement architecture Al99.5 matrix: CTE increases again AlSi7Mg matrix: Si-bridges between SiC

forming a SiC-Si-network prevent an accelerated expansion

Eutectically segregated Si in an Al alloy (e.g. A356) forms a percolating Si network Thermal behaviour of the as-cast alloy is similar to the composite P2 Destruction of the Si network (plastic deformation), lead to a thermal behaviour like matrix with insulated reinforcement (increasing CTEs with rising temperature) These observations on the unreinforced matrix alloy verify the effect of the percolating SiC-Si-network on the thermal expansion of the composite P2

Solution quenched samples of Al-matrix-composites lead to a small additional expansion during a slow 1st heating up cycle, due to formation of overaged incoherent Mg2Si precipitates in the AlSi7Mg matrix alloy & relief of internal stresses from quenching.




Part II

Thermal Expansion Behaviour of Fiber Reinforced

Metal-Matrix Composites




CFR-MMC’s Material

Matrix Pan C-Fibers Vol.Fr.% system

AlMg0.2 T300J 65 Woven 50% warp Bundle vol.fr. 70%

AlMg0.2 T300J 65 Woven 80% warp Bundle vol.fr. 70%

Al99.8 M40B 74 Unidirectional

MgAl0.6 M40 70 Unidirectional

Mg99.8 Tenax HTA 5331 60 Unidirectional

Processing

Gas pressure infiltration




Experimental Procedure for CFR-MMC’s

Load 0.5N

Rate 3K/min

2cycles -40 to 120°C

2cycles -40 to 200°C

0 100 200 300 400 500 600

-50

0

50

100

150

200

Tem

per

atu

re, °

C

Time, min0 100 200 300 400 500 600

-50

0

50

100

150

200

Tem

per

atu

re, °

C

Time, min

Time temperature cycles For micromechanical analysis

Time temperature cycles For micromechanical analysis




Microstructure of CFR-MMC’s

MgAl0.2/C-T300J/65f (0/90°,50/50%), in- plane section

MgAl0.2/C-T300J/65f (0/90°,50/50%), cross- section

MgAl0.2/C-T300J/65f (0/90°,80/20%), in-plane section

MgAl0.2/C-T300J/65f (0/90°,80/20%), cross- section

Al/C-M40B/74f, UD cross section




•Irreversible plastic deformation

CFR-MMC’s Thermal Stresses

Temperature, °C

dl/l

%

•Reversible plastic deformation

Width of hysteresis

Residual stresses

•Elastic deformation

Tcr

•Al

l•C

Fiber Matrix

0

Stresses during cooling




-50 0 50 100 150 200-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

dl/l

%

Temperature, °C

Pure Mg

-50 0 50 100 150 200-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

dl/l

%

Temperature, °C

Pure Mg Mg/C-M40B, long

-50 0 50 100 150 200-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

dl/l

%

Temperature, °C

Pure Mg Mg/C-M40B, long Mg/C-Tenax

-50 0 50 100 150 200-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

dl/l

%

Temperature, °C

Pure Mg Mg/C-M40B, long Mg/C-Tenax Mg/C-T300J,80/20

-50 0 50 100 150 200-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

dl/l

%

Temperature, °C

Pure Mg Mg/C-M40B, long Mg/C-Tenax Mg/C-T300J,80/20 Mg/C-T300J,50/50

-50 0 50 100 150 200-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

dl/l

%

Temperature, °C

Pure Mg Mg/C-M40B, long Mg/C-Tenax Mg/C-T300J,80/20 Mg/C-T300J,50/50 Mg/C-T300J,20/80

-50 0 50 100 150 200-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

dl/l

%

Temperature, °C

Pure Mg Mg/C-M40B, long Mg/C-Tenax Mg/C-T300J,80/20 Mg/C-T300J,50/50 Mg/C-T300J,20/80 Mg/C-Tenax,trans

-50 0 50 100 150 200-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

dl/l

%

Temperature, °C

Pure Mg Mg/C-M40B, long Mg/C-Tenax Mg/C-T300J,80/20 Mg/C-T300J,50/50 Mg/C-T300J,20/80 Mg/C-Tenax,trans Mg/C-M40B, trans

-50 0 50 100 150 200-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

dl/l

%

Temperature, °C

Pure Mg Mg/C-M40B, long Mg/C-Tenax Mg/C-T300J,80/20 Mg/C-T300J,50/50 Mg/C-T300J,20/80 Mg/C-Tenax,trans Mg/C-M40B, trans Mg/C-T300J, out of plane

Thermal Mechanical Analysis (TMA) for CFR-Mg MC’s




-50 0 50 100 150 200-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

dl/l

%

Temperature, °C

Pure Al

-50 0 50 100 150 200-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

dl/l

%

Temperature, °C

Pure Al 0°

-50 0 50 100 150 200-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

dl/l

%

Temperature, °C

Pure Al 0° 45°

-50 0 50 100 150 200-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

dl/l

%

Temperature, °C

Pure Al 0° 45° 90°

Thermal Mechanical Analysis (TMA) for CFR-Al MC’sAl/M40B/74f




Residual stresses after thermal cycling for CFR-MMC’s

-0.03

-0.02

-0.01

0

0.01

0.02

0.03

0.04

120°

C

200°

C

120°

C

200°

C

120°

C

200°

C

120°

C

200°

C

120°

C

200°

C

120°

C

200°

C

Al/M40 Mg/M40 Mg/Tenax Mg/T300,80/20 Mg/T300,50/50 Mg/T300,50/50,out of plane

dl/l

%

max

min

-0.03

-0.02

-0.01

0

0.01

0.02

0.03

0.04

120°

C

200°

C

120°

C

200°

C

120°

C

200°

C

120°

C

200°

C

120°

C

200°

C

120°

C

200°

C

Al/M40 Mg/M40 Mg/Tenax Mg/T300,80/20 Mg/T300,50/50 Mg/T300,50/50,out of plane

dl/l

%

max

min




Inst.CTE vs Thermal cycling

0

0.5

1

1.5

2

2.5

3

3.5

4

-50 0 50 100 150 200 250

Temperature, °C

Inst

.CT

E,

pp

m/K

1st heating Mg/M40

0

0.5

1

1.5

2

2.5

3

3.5

4

-50 0 50 100 150 200 250

Temperature, °C

Inst

.CT

E,

pp

m/K

1st heating Mg/M40

2nd heating Mg/M40

0

0.5

1

1.5

2

2.5

3

3.5

4

-50 0 50 100 150 200 250

Temperature, °C

Inst

.CT

E,

pp

m/K

1st heating Mg/M40

2nd heating Mg/M40

3rd heating Mg/M40

0

0.5

1

1.5

2

2.5

3

3.5

4

-50 0 50 100 150 200 250

Temperature, °C

Inst

.CT

E,

pp

m/K

1st heating Mg/M40

2nd heating Mg/M40

3rd heating Mg/M40

4th heating Mg/M40

0

0.5

1

1.5

2

2.5

3

3.5

4

-50 0 50 100 150 200 250

Temperature, °C

Inst

.CT

E,

pp

m/K

1st heating Mg/Tenax

1st heating Mg/M40

2nd heating Mg/M40

3rd heating Mg/M40

4th heating Mg/M40

0

0.5

1

1.5

2

2.5

3

3.5

4

-50 0 50 100 150 200 250

Temperature, °C

Inst

.CT

E,

pp

m/K


2nd heating Mg/Tenax

1st heating Mg/M40

2nd heating Mg/M40

3rd heating Mg/M40

4th heating Mg/M40

0

0.5

1

1.5

2

2.5

3

3.5

4

-50 0 50 100 150 200 250

Temperature, °C

Inst

.CT

E,

pp

m/K



3rd heating Mg/Tenax

1st heating Mg/M40

2nd heating Mg/M40

3rd heating Mg/M40

4th heating Mg/M40

00.5

11.5

2

2.53

3.54

-50 0 50 100 150 200 250

Temperature, °C

Inst

.CT

E,

pp

m/K 1st heating Mg/Tenax



4th heating Mg/Tenax

1st heating Mg/M40

2nd heating Mg/M40

3rd heating Mg/M40

4th heating Mg/M40

0

0.5

1

1.5

2

2.5

3

3.5

4

-50 0 50 100 150 200 250

Temperature, °C

Ins

t.C

TE

, pp

m/K

10

15

20

25

30

35

40

45

50




4th heating Mg/Tenax

1st heating Mg/M40

2nd heating Mg/M40

3rd heating Mg/M40

4th heating Mg/M40

1st heating Mg/T300J outof plane




Inst.CTE vs Temperature for CFR-Mg MC’s

-10123456789

10

-50 0 50 100 150 200 250

Temperature, °C

Inst

.CT

E,

pp

m/K

Mg/M40,0

-10123456789

10

-50 0 50 100 150 200 250

Temperature, °C

Inst

.CT

E,

pp

m/K

Mg/M40,0

Mg/Tenax

-10123456789

10

-50 0 50 100 150 200 250

Temperature, °C

Inst

.CT

E,

pp

m/K

Mg/M40,0

Mg/Tenax

Mg/T300J,80/20

-10123456789

10

-50 0 50 100 150 200 250

Temperature, °C

Ins

t.C

TE

, pp

m/K

Mg/M40,0

Mg/Tenax

Mg/T300J,80/20

Mg/T300J,50/50

-10123456789

10

-50 0 50 100 150 200 250

Temperature, °C

Inst

.CT

E,

pp

m/K

Mg/M40,0

Mg/Tenax

Mg/T300J,80/20

Mg/T300J,50/50

Mg/T300J,20/80




Al/M40B/74f +

Mg/M40B/70f

Polar diagrams for inst.CTE vs orientation

MgAl0.2/C-T300J/65f (0/90°,50/50%)

MgAl0.2/C-T300J/65f (0/90°,80/20%)




Conclusions

During thermal cycling, all the CFRM exhibit hysteresis of length change between heating and cooling. The level of plastic deformation is represented by the hysteresis’ width.

Total strain, width of hysteresis are strongly dependent on - the fiber properties - thermal history - fiber orientation and arrangement. Residual stresses causing macroscopic deformation are produced by cooling

from above a certain critical temperature Tcr , which depends strongly on the matrix properties at elevated temperatures.

The plastic deformation and the residual stresses are reproduced by following temperature cycles for the same temperature range.

Transverse fibers of more than 20% increase the longitudinal expansion; low expansion in longitudinal direction is compensated by high expansion transverse and out of plane respectively.

Instantaneous coefficient of thermal expansion (CTE) is not material constant for MMC.

T. Huber and A. Mohammed CompTest2003, Châlons-en-Champagne Jan. 2003 Thermal Expansion Behaviour of Metal-Matrix Composites T. Huber, A. Mohammed and.

Documents

si slide

mohammed comptest2003

matrix section

si alsi7mg

metal matrix slide

material p1 material

mmc material p2 section

destroyed si