Aluminium – the wonder metal - Norsk Hydro · Aluminium – the wonder metal ! Hans J. Roven Professor & Director SA Materials. 2. ... •Electron structure •Atomic size & weight

1.

[email protected] Seminar Qatar University: November 24th 2011Aluminium Symposium Qatar University: November 24th 2011

Aluminium Aluminium ––

thethe wonderwonder metalmetal!!

Hans J. RovenHans J. RovenProfessor Professor

& &

DirectorDirector SA MaterialsSA Materials

2.

[email protected] Seminar Qatar University: November 24th 2011

Fundamentals and fundament

1

3.


What is the origin ofthe element aluminium?

Magnesium is made in stars by nuclear fusion oftwo carbon atoms

Then;Aluminium is made in the nuclear fires ofsuch heavy stars – when a proton adds

to a magnesium atom.

1

2

(AP Photo/NASA and ESA)

A violent and chaotic-looking mass of gas and dust is seen in this image of a relatively nearby supernova remnant. Denoted N 63A, the object is theremains of a massive star that exploded, spewing its gaseous layers out

into an already turbulent region, lying 160,000 light-years from our ownMilk Way galaxy.

MgP

Al

4.


The Earth Crust

Al

• The no. 1 metallic element •The 3rd most abundant element

•Constitute 8,23 weight % of Earth Crust

Natural resourceof very high quantity

!

5.


The Bauxite Resource

Total: 55 – 75 billion tonsThe World: Not running out of

Al resources !

6.


Basics of Aluminium

2

7.


Several basic properties of

solid aluminium can be explained by the:

•Electron structure

•Atomic size & weight

•Interatomic bond strength

•Atomic arrangement (FCC)

8.


9.


The Periodic TableColumns: Similar Valence Structure

Adapted from Fig. 2.6, Callister &

Rethwisch 8e.

Electropositive elements:Readily give up electronsto become + ions.

Electronegative elements:Readily acquire electronsto become - ions.

give

up

1e-

give

up

2e-

give

up

3e- iner

t gas

esac

cept

1e

-

acce

pt 2

e-

O

Se

Te

Po At

I

Br

He

Ne

Ar

Kr

Xe

Rn

F

ClS

Li Be

H

Na Mg

BaCs

RaFr

CaK Sc

SrRb Y

3e-

10.


13 protons14 neutrons

13 electrons

Bohr’s atom model of Al

11.


Electron structure & properties

Electron configuration

(stable)

...

...

1s22s22p 63s23p 6 (stable)

Atomic #

18

Element1s11Hydrogen1s22Helium1s22s13Lithium1s22s24Beryllium1s22s22p 15Boron1s22s22p 26Carbon

...

1s22s22p 6 (stable)10Neon1s22s22p 63s111Sodium1s22s22p 63s212Magnesium1s22s22p63s23p113Aluminum

...

Argon

Adapted from Table 2.2, Callister & Rethwisch 8e.

3 valenceelectrons

Forms metallic bonds

easily

+ intermetallicstrengthening

phases

Al

High electr. cond.

Easy: Ions 3+

Electrolysis

12.


Low Density

Aluminium:

Data from Table B.1, Callister & Rethwisch, 8e.

ρ(g

/cm

)3

Graphite/ Ceramics/ Semicond

Metals/ Alloys

Composites/ fibersPolymers

1

2

20

30Based on data in Table B1, Callister

*GFRE, CFRE, & AFRE are Glass,Carbon, & Aramid Fiber-ReinforcedEpoxy composites

10

345

0.30.40.5

Magnesium

ALUMINIUM

Steels

Titanium

Cu,Ni

Tin, Zinc

Silver, Mo

TantalumGold, WPlatinum

GraphiteSilicon

Glass -sodaConcrete

Si nitrideDiamondAl oxide

Zirconia

HDPE, PSPP, LDPE

PC

PTFE

PETPVCSilicone

Wood

AFRE*

CFRE*

GFRE*

Glass fibers

Carbon fibers

Aramid fibers

1) Density similar to ceramics, Si and glass fibres

2) Among most usedmetals, onlyMg has lower weight

13.


• Atoms touch each other along face diagonals.

Face Centered Cubic Structure (FCC)

4slip planes x 3 slip directions=

12 slip systems

Easy formable ref.

Taylor theory

14.


A sites

B B

B

BB

B B

C sites

C C

CA

B

B sites

• ABCABC... Stacking Sequence• 2D Projection

• FCC Unit Cell

FCC Stacking Sequence

B B

B

BB

B B

B sitesC C

CA

C C

CA

AB

C • High Stacking Fault Energy!

(i)Easy recovery(ii) Easy cross-slip(iii) Seldom twin deformation

15.


Easy cross slip and dislocation multiplication

b

� Spreads deformation� Work hardening +� Improves formability

Slip plane 2

Slip plane 1

16.


Oxide thickness

AlSurface Al2O3 oxides form naturally and spontaneously

t: 0.1-2 nm

Al

t: 2 - > 1000 nm

Adding protecting or functionizedoxide layer by anodizing

Corrosion resistant !!

Enhanced corrosionprotection

1

2

Functionalizing; Colours, Heat reflections

17.


Surface Oxide

Very corrosionresistant

Anodizing

18.


Cryogenic and low T properties

Enhanced stiffness and

mechanical properties at low T

The preferred material

Space structures Sport equipment

Aircraft structures

Increased friction stress for dislocations(Peierls stress)

19.


Comparizons –other competing materials?

3

20.


Engineering text

The Cambridge Materials Selector - CMS

Selections:among ~3000 materials

Compares:Specific strength etc..

Optimal mechanical designEco -Sustainability design

21.


Age hardening ALUMINUM ALLOYS The material The high-strength aluminum alloys rely on age-hardening: a sequence of heat treatment steps that causes the precipitation of a nano-scale dispersion of intermetallics that impede dislocation motion and impart strength. General properties Density 2500 - 2900 kg/m^3 Price 1.423 - 2.305 USD/kg Mechanical properties Young's modulus 68 - 80 GPa Elastic limit 95 - 610 MPa Tensile strength 180 - 620 MPa Elongation 1 - 20 % Hardness - Vickers 60 - 160 HV Fatigue strength at 10

7 cycles 57 - 210 MPa

Fracture toughness 21 - 35 MPa.m^1/2 Thermal properties Thermal conductor or insulator? Good conductor Thermal conductivity 118 - 174 W/m.K Thermal expansion 22 - 24 µstrain/°C Specific heat 890 - 1020 J/kg.K Melting point 495 - 640 °C Maximum service temperature 120 - 170 °C Electrical properties Electrical conductor or insulator? Good conductor

Young’s modulus

Definition…………………………………….…………………………………………………………………….………………….

Measurement…………………………………….………………….

Origins…………………………………….………………….

� Definition,

� Measurement, � Science

Thermal expansion

Definition…………………………………….…………………………………………………………………….………………….

Measurement…………………………………….………………….

Origins…………………………………….………………….

22.


Example: E- modulus vs. density

Envelopes can

be added

around families

automatically

23.


The mostly used metals

Steels Aluminium

CopperMagnesium

ZinkNickel, etc

24.


Aluminium

Atomic weight: 26.98Atomic diameter: 2,86ÅDensity: 2.7 g/cm3Melting point: 660,3 CUnit cell: FCC Phase transf.: NO

Thermal cond.: 250Electric cond.: 35T expansion: 22-24E- modulus: 70 GPa

Iron

Atomic weight: 55.85Atomic diameter: 2,48ÅDensity: 7.8 g/cm3Melting point: 1538 CUnit cell: BCCPhase transf.: YES

Thermal cond.: 80Electric cond.: 0.9T expansion: ~15E-modulus: 210 GPa

Metallic Aluminium versus Iron

25.


Metallic Aluminium versus Iron

Atomic weight: 48%

Density: 35%

Melting point: 43%

•Non- magnetic

•Electric cond.: x 39

•Thermal cond.: x 3

• LIGHT (1/3 of steel !!)• Specific strength x 3 !• Specific ductility: Similar• More space for other atoms !• Easier to form (Tm and def. energy )

Thermal activation dislocations easier !

Much more corrosion resistant

26.


Al alloy synthesis

4

27.


Intelligent synthesis

O

Se

Te

Po At

I

Br

He

Ne

Ar

Kr

Xe

Rn

F

ClS

Li Be

H

Na Mg

BaCs

RaFr

CaK Sc

SrRb Y

• Thermodynamic characteristiscs of Al

• High solubility

• Hardening precipitates

• High processability

Tailormake Mechanicaland

Functional properties

28.


• Result:S

~y

1 σ

Large shear stress needed to move dislocation toward precipitate and shear it.

Dislocation “advances” but precipitates act as “pinning” sites with

S.spacing

Side View

precipitate

Top View

Slipped part of slip plane

Unslipped part of slip plane

Sspacing

Mechanical strength(precipitation)

Strength increase up to ~10 x

Dislocation multiplicationby ’Frank Read’ mechanism

29.


Particle cutting

Next dislocation passes more easily because the particle cross section is reduced

30.


150

160

170

180

190

200

1 10 100 1000 10000Ageing time, mins

Har

dnes

s, H

V

12 nm12 nm

Hardness and microstructure evolutions

7050 Al alloy 7050 Al alloy with with

6.29 wt% Zn, 6.29 wt% Zn,

2.22 wt% Mg, 2.22 wt% Mg,

2.28 wt% Cu, 2.28 wt% Cu,

0.11 wt% 0.11 wt% ZrZr, ,

0.09 wt% Fe and 0.09 wt% Fe and

0.05 wt% Si0.05 wt% Si

g002

g111

31.


HAADF STEM

Precipitates in an

Al-Mg-Si-Ge-Cu alloy.

R. Bjørge et al. Submitted.

TEM

Al[100]

32.


3-dimensional atom probe (3DAP)

+

+

yx

Position-sensitive detector

mass spectrometer

DC voltage: 4-14 kV

Pulse voltage : 20% of DC voltage, with a frequency of 1.5kHz

An energy compensated optical position sensitive atom probe (ECOPoSAP) developed at University of Oxford

Ref. Gang Sha, Univ. of Oxford

33.


Microstructure evolutions from 3DAP

60 min30 min 240 min 1440 min

5 nm

At 120°C

Quenched

Ref. Gang Sha, Univ. of Oxford

34.


Atomistic Simulation using potentials from

binary phase diagrams

(a) (c)(b)

A

Zn Mg Cu

Separate Cu and Separate Cu and Zn+MgZn+Mg clustering due to limited solid solubility of Cu clustering due to limited solid solubility of Cu

in Mg or Zn, and limited solubility of Mg in Znin Mg or Zn, and limited solubility of Mg in Zn

Ref. Gang Sha,

Univ. of Oxford

35.


Down-stream

5

36.


All downstream technologies are feasible to Al alloys

Adapted from Fig. 11.8, Callister 7e.

-Forging

Ao Ad

force

dieblank

force-Drawing

tensile force

Ao

Addie

die

-Extrusion

ram billet

container

containerforce

die holder

die

Ao

Adextrusion

-Rolling

roll

Ao

Adroll

All casting techniques

All forming techniques

1

2

Nano - technologies3

37.


Extrusions

High formability High productivity

Complex geometries

Intelligent mechanical design

Integrated Funtional Design(Solar, heat capture/reflection, optical…)

38.


Automotive

Light

Complexshapes

Crash-safety

Functionalizedcomponents

39.


Almost unlimited product possibilites…

Printed foil films Food protection

(light totally reflected)

Kitchen and houshold

Heat collectors

Arts & jewellery Paint powder LCD sputtering target (TV, screens, etc.)

Survival blankets

with Al coatings

40.


Aluminium & students

6

41.


Aluminium – a preferable topic for PhDeducation

PhDs graduated within Aluminium, 1973 - 2010, NTNU

Trend:Numerous PhDs

A lot unexplored research

Industry Relevant

Society impacts

Sustainable !

42.


Attracts young students

43.


Is eveything knownOR

More to explore ?

44.


Going ”nano”Abnormous space & possibilites

7

45.


Nanotechnology

”There is Plenty of

Room at the Bottom”,

Invited talk :

Annual meeting

American Physical

Society, California

Institute of Technology,

December 29th, 1959 Professor Richard P. Feynman1918-1988

”Born” in 1959

46.


Quiz

If we take one and one atom out from 1 mole of aluminium

-then place them in a row (atom by atom)

How long would this row be?

47.


An illustration of one-dimensional depth :

The 1 mole: ~6 x E+23 atoms

1) Place these atoms one by one in one row:

2,86Å=2,86E-10 m

2) Distance = (6xE23) x (2,86xE-10) m = 17,2 x E+13 m =

17,2 x E10 km

3) Pilot an F-16 aerofighter ( ~ 2000 km/hour)

48.


Pilot will travel for

8760 years

to reach the end of 1

mole !!!!!!

49.


The 3D space at atomic scaleis enormous

AluminiumLong term

Opportunities !

50.


(M.P. Liu and H.J. Roven, Appl. Phys. Lett., 90, 083115 (2007))

• Average size: 4 nm

• Mean density: ~1016/m2

Nanostructures in ECAP 6082 Al

51.


Example: “Super-strength”

From:

M. Murashkin, A.R. Kilmametov, R.Z. Valiev,

The Physics of Metals and Metallography,

2008, Vol. 106, No.1, pp. 90-96

Al- 1570

HPT: 950 MPa and 4.5% ductility

52.


Aluminium isthe wonder metal!

53.


Qatar - Doha, November 24th 2011

Thank you all!

54.


55.


Conclusions

• Aluminium is the preferred metal in many sectors and productsegments (light!)

• Excellent casting and forming properties• Corrosion and light reflectional properties are excellent• The mechanical and functional properties are unique• Sustainable – recycling saves energy (~95%) and CO2 (up to

93%)• The availability is almost unlimited• Research opportunities and unexplored areas are significant• Represents challenges and opportunities for the younger

generations• Modern societies and future depends on aluminium

56.


Super high strength Al-xMg

Potentials SPD:

Mg: 300-500 MPa

Al: 400-1000 MPa

Ti: 400-1500 MPa

Specific strength vs. UTS

Very High Potentials

Specific

Strength increaseLight Metals

57.

[email protected] Seminar Qatar University: November 24th 2011NanoSPD5, Nanjing

CP Al - 99.6 wt%Al - 0.5%MgAl -1.0%MgAl- 2.5 %MgAA5182 (4.1%Mg)

58.


Nano sized grain size

• The average grain size considerably decreased as the Mg content

increased.

• Al–0.5Mg alloy: grain size varies 50–200 nm• Al–4.1Mg alloy: grain sizes in the 10–130 nm range

TEM bright-field imagesAl–0.5 MgD ~ 120 nm

GB1GB2

AA5182D ~ 50 nm

Al–1.0 MgD ~ 90 nm

Al–2.5 MgD ~ 70 nm

Al –xMg alloys:

59.


HRTEM [1-10] image Inverse Fourier image

Non-equilibrium HAGB (AA5182)

Inverse Fourier image

HRTEM images of a non-equilibrium HAGB

Local dislocation density

3.8 ×××× 1017

• The neighboring grains C and D share a common [1-1 0] axis

• Extreme density of 60º dislocations near the GB

• Most dislocations appear as dipoles (ellipses) together with loops (circles)

• Such GB should still be referred to as a non-equilibrium GB though the GB plane is almost straight.

ExtremeDislocation density

60.


2 nm2 nm

Z-contrast HAADF STEM images of Ge-containing

precipitates in an Al-Mg-Ge alloy.

Al[100]

Al[100]

R. Bjørge et al. Acta Mater 59 (2011) 6103.

61.


Ram load P

Ram position

P

% Mg2Si Log(strain rate)-1 4

Log(time)

T T T

Extrusion is veryattractive

Phase diagrams

TTT- diagrams

62.


A fundamental problem of extrusion:3D-modelling and simulation of the stability

of flow in thin strip extrusion

Material and heat flow

in the container and die

inlet; microstructure

evolution

Friction and flow in

the bearing channel Stress build-up in

the strip leaving the

die; stability of

flow

Variability of thickness,

shape, microstructure in

the strip over a press cycle

Thin

walled

sections

Documents

Aluminium – the wonder metal - Norsk Hydro · Aluminium – the wonder metal ! Hans J. Roven Professor & Director SA Materials. 2. ... •Electron structure •Atomic size & weight