Effects of Electric Current Treatment on Thermal Conductivity of Al-X-Y-Cu Alloy

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Effects of Electric Current Treatment

on Thermal Conductivity of Al-X-Y-Cu Alloy

Jae-Cheol Jang (xH. J. Jung) Jun. 19, 2017

Magnesium Technology Innovation Center

School of Materials Science and Engineering

Seoul National University, Seoul 08826, Korea

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Contents

 Introduction

 Experimental Procedures

 Materials and Gravity Casting

 Electric Current Treatment

 Thermal Diffusivity Test

 Results

 Temperature during Current Treatment

 Thermal Diffusivity

 Conclusion

 Future Work

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Introduction

 Applications for Electronic Devices

Ref. Global Heat Sinks Market by Manufacturers, Contries, Type and Application, Forecast to 2022, Global Info Research (2017)

Heat Sink Products for Electronic Devices

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Introduction

 Applications for Automobile Industry

Fig. Selected promising applications in automobile industry by Rio Tinto Ref. KPMG's Competence Centre Automotive, LMC

World EV Market Share_ IHS

Battery Heat Sink for EV Engine Heat Sink LED Heat Sink

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Introduction

 Thermal Conductivity of Materials

Fig. Spread of λ values for three status of matter.

Fig. Thermal conductivity of some materials as a functions of temperatures.

Ref. James R. Welty, Fundamentals of Momentum, Heat and Mass Transfer, Wiley, pp. 201.

Davis T. W., Thermal Conductivity Values., Thermopedia.com

 Thermal Conductivity Value of Metals

(W/m*K), @R.T.

Ag 429 > Cu 401 > Au 317

> Al 237 > Mg 159 > Zn 113 > Fe 67

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Introduction

Ref. F. Stadler et. al., MSEA, 560 (2013) 481-491.

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0.65 0.70 0.75 0.80 0.85 40

60 80 100

NX430-MZM NX430

NX410-MZM NX410

N4

T h er m a l D iffu si ti v ity ( mm

2

/s )

Mole Fraction of Primary Al Phase

0.0 0.4 0.8 1.2 1.6

40 60 80 100

N4

NX430-MZM NX410-MZM NX430

T h er m a l D iffu si ti v ity ( mm

2

/s )

Percent of Solute Elements in

α

-Al Phase (%)

NX410

N4 NX410 NX430 NX410-

MZM

NX430- MZM α-Al

(Calculated) 0.8408 0.7997 0.7043 0.7973 0.7004

Solute Elements in α-Al

(at.%), (Calculated) 0.0229 0.2466 0.4098 1.3538 1.6571

Thermal Conductivity

(W/m*K), (Calculated) 207.04 193.72 175.06 162.54 145.58

Thermal Diffusivity

(mm²/s), (Measured) 95.385 60.326 49.439 49.094 44.064

Introduction



Thermal Property vs. (Solute Elements in α -Al) and ( α -Al Fraction)

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Concept Pros Cons

Heat Treatable

Alloy

Adding Soluble Elements T4 or T6 Treatment After

Casting

Good Mechanical Prop.

with Good Thermal Cond.

Low Productivity (Time and Cost for Heat

Treatment)

Combining of Microporosity (Especially, Die-cast Product)

Non- Heat Treatable

Alloy

Designed to present good property in as-cast state

Non-soluble

High Productivity Cost-Effective

Intermediate Mechanical Prop. and Thermal Cond.

Introduction



Pros & Cons of Die-Cast Alloys by Alloy Types

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Experimental Procedures

 Materials

 Al-xat.%X-yat.%Y-1.0at.%Cu

 Melting Condition

 Melting Temp: 750

^o

C

 Crucible: Graphite

 Melt Weight: 1.6kg

 No Protective Gas

 Melt was poured

into pre-heated

steel mold.

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Experimental Procedures

 Electric Current Treatment

 Current Density (A/mm

²

): 80 (Fixed)

 Time for 1 Pulse (ms): 400, 500, 550, 600

 Temperature were measured

by FLIR system.

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 Thermal Conductivity Measurement



Temperature: 25

^o

C



Number of Shots: 5 Shots for Each Sample

Experimental Procedures

<Fig. Thermal Diffusivity Measuring Machine, LFA 457 (Left),

Disc Type Sample (12.7mm*2t) (Right)>

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Results

 Current Treatment: Temperature – 10 Pulses

0 20 40 60 80

0 50 100 150 200 250

Temperature (o C)

Time (sec)

0 20 40 60 80 100

0 50 100 150 200 250 300

Temperature (o C)

Time (sec)

0 20 40 60 80 100

0 50 100 150 200 250 300

Temperature (o C)

Time (sec)

0 20 40 60 80 100

0 50 100 150 200 250 300 350

Temperature (o C)

Time (sec)

T_max.=169.89, T_min.=150.72 T_avg.=162.26 400A-10Pulses

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0 50 100 150 200 250 300 0

50 100 150 200 250 300 350

Temperature (o C)

Time (sec)

0 50 100 150 200 250 300

Temperature (o C)

Time (sec)

0 50 100 150 200 250 300

Temperature (o C)

Time (sec)

0 50 100 150 200 250

Temperature (o C)

Time (sec)

Results

 Current Treatment: Temperature – 30 Pulses

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Time (ms) T

_min.

(

^o

C) T

_max.

(

^o

C) T

_avg.

(

^o

C) T

_max.

-T

_min.

(

^o

C)

10 Pulses (800A)

400 150.72 169.89 162.26 19.17

500 203.87 220.88 214.98 17.01

550 193.55 204.41 199.51 10.86

600 275.38 296.95 288.26 21.57

30 Pulses (800A)

400 174.70 218.67 198.09 43.97

500 211.95 259.26 239.30 47.31

550 206.32 255.22 233.36 48.9

600 265.68 318.18 297.07 52.5

Results

 Current Treatment: Temperature

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10 Pulses 30 Pulses

Time(ms) 400 500 550 600 400 500 550 600

Thermal Diffusivity

(mm

²

/s)

49.6704 50.576 54.4724 49.094 44.482 48.3692 47.6318 47.7686

St. Dev. 0.0496 0.0501 0.0720 0.0136 0.0380 0.0348 0.0554 0.0378

Results

 Thermal Diffusivity

300 400 500 600 700

40 45 50 55 60

Thermal Duffusivity O State: 54.48 T Sample: 46.50

T h er m a l D iffu si v ity ( mm

2

/s )

Time per Pulse (ms)

Current Density: 80 A/mm²

10 Pulses 30 Pulses

As-cast

Test Sample

300 400 500 600 700

100 150 200 250 300 350 400

T em p era tu re (

o

C )

Time per Pulse (ms)

30 Pulses 10 Pulses

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Conclusion

 Electric Current Treatment



Electric Current was applied to Al-X-Y-1Cu alloy successfully.



Temperature of the sample was depending on current time and the number of pulses.

 Thermal Diffusivity (Thermal Conductivity)



There was big change with applying electric current treatment.



Thermal diffusivity of the samples in initial ECT stage is relatively low, but, diffusivity value was increased with pulse time and temperature.



Clear evidence of decrement in thermal diffusivity is not found,

though artificial aging might be occurred.

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Future Work

 Microstructure Analysis



SEM analysis: Grainsize and Precipitate

 Hardness Measurement



Effects of Electric Current Treatment on Mechanical Property

 Modification of Alloy Composition



High Concentration of Soluble Element Alloy

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[at.%]



Al – Ca, Cr, Cu, Fe, Li, Mg, Ni, Si, Sn, Sr, Zn

Al-Cu

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Thank You

for Your Kind Attention

Effects of Electric Current Treatment on Thermal Conductivity of Al-X-Y-Cu Alloy