SOFT MAGNETIC NANOCRYSTALLINE POWDERS PRODUCED BY … · 2007. 6. 26. · the canted spin configuration in smal particles the non-equilibrium cation redistribution resulting in a

ARM-4, Constanta, 5 September 2005, 1

SOFT MAGNETIC NANOCRYSTALLINE SOFT MAGNETIC NANOCRYSTALLINE POWDERS PRODUCED BY POWDERS PRODUCED BY

MECHANICAL ALLOYING TECHNIQUESMECHANICAL ALLOYING TECHNIQUES

Ionel Chicinaş

Department of Materials Science and Technology, Technical University of Cluj-Napoca, Romania


Soft magnetic nanostructures

Small ferromagnetic crystallites coupled by exchange interaction

Local anisotropy Model D< Lex

Local anisotropies are randomly averagedout by exchange interactions → there is not any anistropy net effect on the magnetisation process

Low coercivity and high permeability

63

41 DAM

KpMKpH

SStc

StcC ≈

><=

6410

32

0

2/1 D

KAMp

KMp StSt

i ⋅⋅

≈=μμ

μ μμ

G. Herzer, Mater. Sc. & Eng. , A133 (1991), 1-5 & Physica Scripta, T49 (1993), 307-314


G. Herzer, Mater. Sc. & Eng. , A133 (1991), 1-5 & Physica Scripta, T49 (1993), 307-314

Nanocrystallinesoft magnetic materials

partial crystallisation

Amorphous SM materials

63

41 DAM

KpMKpH

SStc

StcC ≈

><=

6410

32

0

2/1 D

KAMp

KMp StSt

i ⋅⋅

≈=μμ

μ μμ

two-phase materials:nanocrystallites in anamorphous matrix


Mechanical alloying (MA)involves the synthesis of materials by high-energy milling

Ω

Disc

Vialω

Mechanical milling (MM) refers to the process of milling pure metals or compounds whithout solid state reaction

Ω » ω → shock mode process (SMP)

Ω « ω → friction mode process (FMP)

R. Hamzaoui, O. Elkedim, E. Gaffet, Mater. Sci. Eng. A 381 (2004) 363-371

Mechanical routes for producing nanocristalline powders


D1

D2

D1

B1

B1

B2

C1

C2

C3


A BA Bn m

Ener

gia

libeă

Aliaj amorf

Amestec al componenţilor A şi B

Compus intermetalic cristalin

1

2

3

H.K.D.H. Bhadeshia, Mater. Sci. Techn. 16 (2000) 1404-14011

C.C. Koch, J.D. WhittenbergerIntermetallics, 4 (1996) 339

MAAC MAAC – can reduce the synthesis time!

Mechanical Alloying and Annealing Combining (MAAC) -What is this technique?

MA

Generally, synthesis of new material by MA needs a long time

What's happening if we STOP the milling process before the mechanical alloying finishing and then we make an annealing?

It is `possible to improve (finishing) the solid state reaction of compound/alloy forming!

Annealing the mixture milled


V. Pop, O. Isnard and I. Chicinas, J. Alloys and Comp., 361 (2003), p.144-152.


Reactive milling (RM)Mechanochemistry (MC)

(dry or wet MM)

The MC consists of:

a. reduction of the grain size below a certain value

b. the subsequent chemical reaction towardsthe equilibrium phase composition underthe milling conditions.


80

20

40

60

0

100

τ0 τ1 τ3τ2 τ4time

germi-nation development Saturation/

finishinginitiation

20%Ni3Fe+80%(3Ni+Fe)

80

20

40

60

0

100

Ni 3F

e pe

rcen

tage

τ0 τ1 τ3τ2 τ4time

development Saturation/finishinginitiation

3Ni+Fe

20%Ni3Fe+

Mechanical Alloying in the Presence of Nanocrystalline Germs of the same Product

nm BAnBmA =+ nmnm BABAxnBmAx =⋅++⋅− )()1(

Z. Sparchez, I. Chicinas, O. Isnard, V. Pop, F. Popa, presented at ISMANAM 2005, Paris, to be published

ZnFe

2O4,

CuF

e 2O4,

MeFe2 O

4

Me = Mg, Cu, Ni,


Mechanical routes for producing of ferrites

Annealing producesonly spinel phase

Polycrystalline ferrite produced by solid state

reaction(ceramic method)

Stoichiometric mixture of oxides or of oxides and hidroxicarbonate

Low temperature chemical coprecipitation

(nanosized ferrite)

Mechanical milling(dry or wet milling)

Mechanical milling(dry or wet milling)

Mechanochemistry(dry or wet milling)

Soft magnetic nanocrystalline (nanosized) ferrites

≈80-95 % spinel phase

MeFe2O4, Me = Mn, Cu, Zn, Ni

ZnFe2O4


Partial reversibility during milling of the reaction:

G.F. Goya, H.R. Rechenberg, J. Phys: Condens. Mater., 10 (1998) 11829-11840G.F. Goya, H.R. Rechenberg, J.Z. Jiang, J. Appl. Phys. 84 (1998) 1101-1108F .Padella et al. Mater. Chem. Phys. 90 (2005) 172-177

α-Fe2O3 + MeO ↔ MeFe2O4

Structural properties, phase composition

The particles contain severalrelated Fe–Me–O phases

Milling in closed vial: α-Fe2O3 is reduced at Fe3O4

Milling in open vial:neither reduction of Fe3+ were detected

Particle size is generaly reduced under 10 nm


Magntic behoviour of mechanosyntesized ferrites

The magnetic properties areassociated with

the canted spin configuration in smal particles

the non-equilibrium cation redistribution resulting in a decrease of the number of magnetic Fe3+(A)-O2--Fe3+(B) linkages

Coexistence of both ferrimagnetic and superparamagnetic phase

Magnetisation does not saturated even in an appliet field of 9 T

The hysteresis loop is not symmetrical about the origin and is shifted to the left

∆HC which increases with increasing the milling time


G.F. Goya, H.R. Rechenberg, J.Z. Jiang, J. Appl. Phys. 84 (1998) 1101-1108

4.2 K 300 K

CuFe2O3

•Ms decrease with milling time as a result of spin canting effect•Upon increasing milling time nanometer-sized CuFe2O4 particles decompose, forming α-Fe2O3 – a furthes decrease of magnetisation

•At higher milling time α-Fe2O3 is reduced at Fe3O4 and MS increase•At 300 K a superparamagnetic behaviour in very smal particles appears


Mechanical routes used for producing SMA

MA MAAC Two-step MA MAACwith inoculated germsMC*

MM of oxides blend

reduction of oxides

alloying by heat treatment

obtaining nanocrystalline alloy by MA

obtaining nanocrystalline alloy by MM

*X.Y. Qin, S.H. Cheong, J.S. Lee, Mater. Sci. Eng., A 363 (2003) 62

Soft Magnetic Nanocrystalline Powders

Raw materials used – generaly elemental powdersMilling equipment used - generaly planetary ball millBall/powder mass ratio : very different (from 5:1 to 30:1)


Alloys Composition

Structure Some magnetic properties GeneralRef.

FexNi1-x, x = 7.69, 9.09, 11.11 at%

bcc and fcc phase mixture for x = 7.69 and 9,09 and only bcc phase for x = 11.11 at% [38]

Ni doping decreases the resonance frequency, but enhances the frequency stability [38]

38

Fe-10 wt% Ni bcc solid solution [21] •HC = 200A/m after 96 h milling [30]•HC = 1600 A/m for shock power mode milling conditions [32]

21, 30- 33, 40

Fe-15 wt% Ni bcc solid solution [46] high value of complex permeability in 1-10 GHz [46]; 46

Fe-20 wt% Ni α-Fe(bcc) + Ni(fcc) →α’-Fe(bct) [34]bcc phase [21]

•Ms = 219 Am2/kg [30]•HC= 110A/m after 96 h milling [30]•HC = 1420 A/m for shock power mode milling conditions [32]

19, 21, 24, 30-34, 40

Fe-25 wt% Ni α-Fe(bcc) + Ni(fcc) →α’-Fe(bct) [34]

34

Fe-30 wt% Ni α-Fe(bcc) + Ni(fcc) →α’-Fe(bct) [26, 34]

26, 34

Fe-35 wt% NiFe-35 at% Ni

α-Fe(bcc) + Ni(fcc) →α’-Fe(bct) → γ(fcc) [34]final structure α’-Fe(bct) + γ(fcc) [26]

•Invar anomaly for 35 at% was not detected [24]•larger TC than that for equilibrium alloys [24]

19, 24, 26, 31, 34

Fe-50at%NiFe-50wt%Ni

γ (fcc) after 22 h [24] larger TC than that for equilibrium alloys [24] 15, 19, 24, 31, 37

Ni3Fe cfc, disordering by milling time [24]

•HC=800A/m pt D = 11 nm [20];•HC increases with increase milling time [22];•there is a fall in the Ms for the 70h milling due to the presence of super paramagnetic particles [25];•Ms decreases at milling time longer than 20 h, due to presence of anti-site disorder [29,41,42].

15, 20, 22, 23, 25, 28, 29, 41 - 43

Soft magnetic nanocrystalline powder from Fe-Ni system


It has been proved that the milling performed in the friction mode (FMP) leads to the formation of alloys exhibiting a soft magnetic behaviour. However, magnetisation is not affected by the mode used

In high-energy ball milling process the fcc solid solution γ(Fe,Ni) in alloys Fe65Ni35 was formed after 36 hours, while in the low-energy milling process the Fe lines disappeared after 400 hours of milling.

Influence of the milling intensities on the magnetic properties and of the structure and local atomic order of Ni atoms was observed in both two processes.

R. Hamzaoui, O. Elkedim, E. Gaffet, J. Mater. Sci., 39 (2004) 5139

General properties depending of milling conditions

E. Jartych, J.K. Żurawicz, D. Oleszak, M. Pękała, J. Magn. Magn. Mater. 208 (2000) 221

E. Jartych, J.K. Żurawicz, D. Oleszak, M. Pękała, J. Magn. Magn. Mater. 208 (2000) 221E. Jartych, J. Magn. Magn. Mater., 265 (2003) 176

Ni3Fe

Ni

Inte

nsité

(u.a

.)

2 t h e t a8 9 . 2 9 0 9 1 9 2 9 3 9 4 9 5

1h1h+ 330°C/1h2h2h+ 330°C/1h3h3h+ 330°C/1h4h4h+ 330°C/1h6h6h+ 330°C/1h8h8h+ 330°C/1h10h10h+ 330°C/1h12h12h+ 330°C/1hss

90 91 92 93 94 95

2 θ (°)

Inte

nsity

(a.u

.)

ss1h1h+330°C/1h2h2h+ 330°C/1h3h3h+330°C/1h

4h4h+330°C/1h6h6h+330°C/1h

8h8h+330°C/1h10h10h+330°C/1h12h12h+330°C/1h

Inte

nsité

(uni

t. ar

b.)

2 theta (degrés)36 40 50 60 70 80 9040 50 60 70 80 90

2 θ (°)

Inte

nsity

(a.u

.)

Fe Fe

Ni3Fe

Ni

peaks shift to LOWER 2θ angles

peaks shift to HIGHER 2θ angles

broadening of the diffraction peaks

•Ni3Fe phase formation•the first order internal stresses

relaxion of the first order internal stresses

the second order internal stresses

I. Chicinas et al. J. Alloys and Compounds 352 (2003), p. 34-40.

Improve the solid state reaction

Relax the internal stresses

Annealing effect

88 90 92 94 9

Inte

nsity

(a.u

.)

2 theta (degrees)88 90 92 94 9

Ni3Fe Ni

88 89 90 91 92 93 94 952 θ (°)

1 h2 h3 h4 h6 h8 h

10 h12 h14 h16 h20 h24 h

as milled

1 h2 h3 h4 h6 h8 h

10 h12 h

+300°C/30min

1 h2 h3 h4 h6 h8 h

10 h12 h14 h16 h20 h24 h

+330°C/1h

1 h2 h3 h4 h6 h8 h

10 h12 h

+330°C/3h

+330°C/8h

1 h2 h3 h4 h6 h8 h

10 h12 h

+330°C/12h

ss

Inte

nsity

(a.u

.)

88 90 92 94 9

Inte

nsity

(a.u

.)


Ni3Fe Ni

88 89 90 91 92 93 94 952 θ (°)

1 h2 h3 h4 h6 h8 h

10 h12 h14 h16 h20 h24 h

as milled

1 h2 h3 h4 h6 h8 h

10 h12 h14 h16 h20 h24 h

as milled

1 h2 h3 h4 h6 h8 h

10 h12 h

+300°C/30min

1 h2 h3 h4 h6 h8 h

10 h12 h

+300°C/30min

1 h2 h3 h4 h6 h8 h

10 h12 h14 h16 h20 h24 h

+330°C/1h

1 h2 h3 h4 h6 h8 h

10 h12 h14 h16 h20 h24 h

+330°C/1h

1 h2 h3 h4 h6 h8 h

10 h12 h

+330°C/3h

1 h2 h3 h4 h6 h8 h

10 h12 h

+330°C/3h

+330°C/8h

1 h2 h3 h4 h6 h8 h

10 h12 h

+330°C/12h

+330°C/8h

1 h2 h3 h4 h6 h8 h

10 h12 h

+330°C/12h

ss

Inte

nsity

(a.u

.)

(311)

One annealing time Different milling time


8 8 9 0 9 2 9 4 9

Inte

nsity

(a.u

.)


88 8 9 9 0 9 1 9 2 9 3 9 4 9 52 θ (°)

0 h0 .5 h

1 h2 h3 h

1 2 h

m illed 1 h

ss

0 h0 .5 h

1 h2 h3 h

1 2 h

m illed 2 h

0 h0 .5 h

1 h2 h3 h

1 2 h

m illed 3 h

0 h0 .5 h

1 h2 h3 h

1 2 h

m illed 4 h

0 h0 .5 h

1 h2 h3 h8 h

m illed 6 h

0 h0 .5 h

1 h2 h3 h8 h

m illed 8 h

0 h0 .5 h

1 h2 h3 h8 h

m illed 1 0 h

0 h0 .5 h

1 h2 h3 h8 h

m illed 1 2 h

0 h1 h m illed 1 4 h0 h1 h m illed 1 6 h0 h1 h m illed 2 0 h

0 h1 h m illed 2 4 h

N i3F e N i

Inte

nsity

(a.u

.)

8 8 9 0 9 2 9 4 9

Inte

nsity

(a.u

.)


88 8 9 9 0 9 1 9 2 9 3 9 4 9 52 θ (°)

0 h0 .5 h

1 h2 h3 h

1 2 h

m illed 1 h

ss

0 h0 .5 h

1 h2 h3 h

1 2 h

m illed 2 h

0 h0 .5 h

1 h2 h3 h

1 2 h

m illed 3 h

0 h0 .5 h

1 h2 h3 h

1 2 h

m illed 4 h

0 h0 .5 h

1 h2 h3 h8 h

m illed 6 h

0 h0 .5 h

1 h2 h3 h8 h

m illed 8 h

0 h0 .5 h

1 h2 h3 h8 h

m illed 1 0 h

0 h0 .5 h

1 h2 h3 h8 h

m illed 1 2 h



8 8 9 0 9 2 9 4 9

Inte

nsity

(a.u

.)


88 8 9 9 0 9 1 9 2 9 3 9 4 9 52 θ (°)

8 8 9 0 9 2 9 4 9

Inte

nsity

(a.u

.)


88 8 9 9 0 9 1 9 2 9 3 9 4 9 52 θ (°)

0 h0 .5 h

1 h2 h3 h

1 2 h

m illed 1 h

ss

0 h0 .5 h

1 h2 h3 h

1 2 h

m illed 2 h

0 h0 .5 h

1 h2 h3 h

1 2 h

m illed 3 h

0 h0 .5 h

1 h2 h3 h

1 2 h

m illed 4 h

0 h0 .5 h

1 h2 h3 h8 h

m illed 6 h

0 h0 .5 h

1 h2 h3 h8 h

m illed 8 h

0 h0 .5 h

1 h2 h3 h8 h

m illed 1 0 h

0 h0 .5 h

1 h2 h3 h8 h

m illed 1 2 h



0 h0 .5 h

1 h2 h3 h

1 2 h

m illed 1 h

0 h0 .5 h

1 h2 h3 h

1 2 h

m illed 1 h

ss

0 h0 .5 h

1 h2 h3 h

1 2 h

m illed 2 h

0 h0 .5 h

1 h2 h3 h

1 2 h

m illed 2 h

0 h0 .5 h

1 h2 h3 h

1 2 h

m illed 3 h

0 h0 .5 h

1 h2 h3 h

1 2 h

m illed 3 h

0 h0 .5 h

1 h2 h3 h

1 2 h

m illed 4 h

0 h0 .5 h

1 h2 h3 h

1 2 h

m illed 4 h

0 h0 .5 h

1 h2 h3 h8 h

m illed 6 h

0 h0 .5 h

1 h2 h3 h8 h

m illed 6 h

0 h0 .5 h

1 h2 h3 h8 h

m illed 8 h

0 h0 .5 h

1 h2 h3 h8 h

m illed 8 h

0 h0 .5 h

1 h2 h3 h8 h

m illed 1 0 h

0 h0 .5 h

1 h2 h3 h8 h

m illed 1 0 h

0 h0 .5 h

1 h2 h3 h8 h

m illed 1 2 h

0 h0 .5 h

1 h2 h3 h8 h

m illed 1 2 h

0 h1 h m illed 1 4 h0 h1 h m illed 1 4 h0 h1 h m illed 1 6 h0 h1 h m illed 1 6 h0 h1 h m illed 2 0 h0 h1 h m illed 2 0 h

0 h1 h m illed 2 4 h0 h1 h m illed 2 4 h

N i3F e N iN i3F e N i

Inte

nsity

(a.u

.)

One milling timeDifferent annealing time


Ni3Fe produced by MAAC

2 θ (°)

8 9 0 9 2 9 4

Inte

nsity

(a.u

.)

2 t h e t a ( d e g r e e s )8 8 9 0 9 2 9 4 9

Inte

nsity

(a.u

.)

88 89 90 91 92 93 94 95

ss

0 h

0.5 h1 h2 h

3 h12 h

milled 1 h

0 h0.5 h

1 h2 h3 h

12 h

milled 4 h

0 h0.5 h

1 h2 h3 h8 h

milled 6 h

2 θ (°)

8 9 0 9 2 9 4

Inte

nsity

(a.u

.)

2 t h e t a ( d e g r e e s )8 8 9 0 9 2 9 4 9

Inte

nsity

(a.u

.)

88 89 90 91 92 93 94 95

ss

0 h

0.5 h1 h2 h

3 h12 h

milled 1 h

0 h0.5 h

1 h2 h3 h

12 h

milled 4 h

0 h0.5 h

1 h2 h3 h8 h

milled 6 h

0 h

0.5 h1 h2 h

3 h12 h

milled 1 h

0 h

0.5 h1 h2 h

3 h12 h

milled 1 h

0 h0.5 h

1 h2 h3 h

12 h

milled 4 h

0 h0.5 h

1 h2 h3 h

12 h

milled 4 h

0 h0.5 h

1 h2 h3 h8 h

milled 6 h

0 h0.5 h

1 h2 h3 h8 h

milled 6 h

(311)

θβλ

cos21 ⋅

⋅= kd

21β - FWHM

d = 12 nm - 52 h milling22 nm - 24 h milling



R. Hamzaoui, O. Elkedim, N. Fenineche, E. Gaffet, J. Craven, Mater. Sci. Eng. A 360 (2003) 299-305

A strong decrease of the coercive field versus crystallite size appearsespecially for crystallite size smaller than 20 nm

Magnetic properties


0

0.3

0.6

0.9

1.2

0 100 200 300 400 500 600 700 800

ss12 h

M2 (a

.u.)

T(oC)

TC(Ni)

TC(Ni

3Fe)

TC(Fe)

I. Chicinas, V. Pop and O. Isnard, J. Magn. Magn. Mater. 242-245 (2002) p. 885-887

3.8

3.9

4.0

4.1

4.2

4.3

4.4

4.5

0 10 20 30 40 50 60

4 K295 K

Ms (µ

B/f.

u.)

Tem ps de broyage (h)

recuit

3.8

4

4.2

4.4

4.6

4.8

0 5 10 15 20 25

not annealed300°C/30min330°C/1h330°C/3h330°C/8-12h

Ms (µ

Bf.u

.)

milling time (hours)

T = 4 K

T = 300 K

*H. Hasegawa, J. Kanamori, J. Phys. Soc. Jap. 33 (1972) 1599

Fe1-xNixin the reach nickel region*

x MFe and MNi=ct.

MNi-Fe when Ni3Fe %


annealed


I. Chicinas, V. Pop and O. Isnard, J. Magn. Magn. Mater. 242-245 (2002) p. 885-887


3.8

3.9

4.0

4.1

4.2

4.3

4.4

0 0.5 1 1.5 2 2.5 3 3.5

M (µ

B/f.

u.)

annealing time (hours)

T = 300 K

ss 1 h

2 h

3 h

4 h

6 h

8 hx 10 ho 12 h

4.0

4.1

4.2

4.3

4.4

4.5

4.6

4.7

0 0.5 1 1.5 2 2.5 3 3.5

M (µ

B/f.

u.)

annealing time(hours)

T = 4 K

ss

1 h

2 h

3 h

4 h

6 h

8 hx 10 ho 12 h



Influence of the milling and annealing conditions on the Ms


0.00

0.50

1.00

1.50

2.00

0 2 4 6 8 10 12

(Mt-M

0)/M0 (%

)


milled 4 h

milled 6 h

milled 8 h

T = 330 °C


Influence of the milling and annealing conditions on the Ms



0

20

40

60

80

100

0 10 20 30 40 50 60In

tens

ité M

ossb

auer

(%)

Temps de broyage (h)

Ni3Fe

α-FeMös

sbau

erin

tens

ity (%

)


0h

3h

4h

8h

10h

12h

Velocity ( mm / s )

0-10 +10

0.96

1.00

Absorption ( %

)

0.96

1.00

Absorption ( %

)

0.97

1.00

Absorption ( %

) 0.98

1.00

Absorption ( %

)

0.99

1.00

Absorption ( %

)

0.98

1.00

Absorption ( %

)

16h

24h

40h

48h

52h

52hannealed

Velocity ( mm / s )

0-10 +10

0.99

1.00

Absorption ( %

)

0.99

1.00

Absorption ( %

)

0.98

1.00

Absorption ( %

) 0.98

1.00

Absorption ( %

)

0.98

1.00

Absorption ( %

)

0.98

1.00

Absorption ( %

)

Speed (mm/s)-10 0 +10

Speed (mm/s)-10 0 +10

Abs

orpt

ion

(%)

Abs

orpt

ion

(%)

Mössbauer spectrometryNi3Fe powders

I. Chicinas, V. Pop, O. Isnard, J.M. Le Breton and J. Juraszek, J. Alloys and Compounds 352 (2003), p. 34-40


0.0

2.0

4.0

6.0

8.0

10.0

12.0

0 0.5 1 1.5 2 2.5 3

mill

ing

time

(hou

rs)


0.0

2.0

4.0

6.0

8.0

10.0

12.0

0 0.5 1 1.5 2 2.5 3

mill

ing

time

(hou

rs)


Ni Fe3

M = const.s

Ni+Fe+Ni Fe (Ni-Fe) 3

330 C o

T >330 C1 o

T >T2 1

Milling – Annealing - Transformation (MAT) diagram

Mechanical Alloying and Annealing Combining technique




Nanocrystalline soft magnetic powders from Fe-Ni-X systems

FeNi3)xAg1-x, Ni50Al50-xFex , Fe49Ni46Mo5, Fe42Ni40B18 , Ni-15%Fe-5%Mo and Ni-16%Fe-5%Mo (wt%) and others

The presence of Ag in (FeNi3)xAg1-x alloys increases the coercive field as compared to the value of Ni3Fe

Both Mo and B have a dramatic effect on the MA process and magnetic properties of Fe-Ni-based materials, mainly by changing the thermodynamic and kinetics of amorphysation and nanocrystal formation

350 °C/4h

350 °C/2h

350 °C/1h

350 °C/30 min

ss

as milled

Ni3Fe

800

700

600

500

400

300

200

100

040 50 60 70 80 90 100 110

2 Theta (°)In

tens

ity (a

.u.)

350 °C/4h

350 °C/2h

350 °C/1h

350 °C/30 min

ss

as milled

Ni3Fe

800

700

600

500

400

300

200

100

040 50 60 70 80 90 100 110

2 Theta (°)

350 °C/4h

350 °C/2h

350 °C/1h

350 °C/30 min

ss

as milled

Ni3Fe

800

700

600

500

400

300

200

100

0

350 °C/4h

350 °C/2h

350 °C/1h

350 °C/30 min

ss

as milled

Ni3Fe

350 °C/4h

350 °C/2h

350 °C/1h

350 °C/30 min

ss

as milled

Ni3Fe

350 °C/4h

350 °C/2h

350 °C/1h

350 °C/30 min

ss

as milled

Ni3Fe

350 °C/4h

350 °C/2h

350 °C/1h

350 °C/30 min

ss

as milled

Ni3Fe

800

700

600

500

400

300

200

100

040 50 60 70 80 90 100 110

2 Theta (°)In

tens

ity (a

.u.)

350 °C/4h

350 °C/2h

350 °C/1h

350 °C/30 min

as milled

Ni3Fe

ss

40 50 60 70 80 90 100

2 Theta (°)

800

700

600

500

400

300

200

100

0

Inte

nsity

(a.u

.) 350 °C/4h

350 °C/2h

350 °C/1h

350 °C/30 min

as milled

Ni3Fe

ss

40 50 60 70 80 90 100

2 Theta (°)

800

700

600

500

400

300

200

100

0

350 °C/4h

350 °C/2h

350 °C/1h

350 °C/30 min

as milled

Ni3Fe

ss

40 50 60 70 80 90 100

2 Theta (°)

350 °C/4h

350 °C/2h

350 °C/1h

350 °C/30 min

as milled

Ni3Fe

ss

40 50 60 70 80 90 100

2 Theta (°)

350 °C/4h

350 °C/2h

350 °C/1h

350 °C/30 min

as milled

Ni3Fe

ss

350 °C/4h

350 °C/2h

350 °C/1h

350 °C/30 min

as milled

Ni3Fe

ss

350 °C/4h

350 °C/2h

350 °C/1h

350 °C/30 min

as milled

Ni3Fe

ss

40 50 60 70 80 90 100

2 Theta (°)

800

700

600

500

400

300

200

100

0

Inte

nsity

(a.u

.)

8 hours milling 6 hours milling

θβλ

cos21 ⋅

⋅= kd

21β - FWHM

d = 11 nm - 16 h milling and annealing at 350 °C for 2 hoursin order to remove second order internal stresses

Supermalloy synthesis by MAAC:• 8 hours milling• different annealing conditions.

I. Chicinas, O. Isnard, V. Pop, J. Mater. Sci. 39 (2004), p. 5305-5308 O. Isnard, V. Pop, I. Chicinaş, J. Magn. Magn. Mater. 290-291 (2005), p. 1535-1538.


O. Isnard, V. Pop, I. Chicinaş, J. Magn. Magn. Mater. 290-291 (2005) 1535

Y. Shen, H.H. Hng, J.T. Oh, J. Alloys Comp. 379 (2003) 266-271.

the mechanical alloying process occurs in two steps

an intermediate amorphous or poorlycrystallined phase, (Ni,Fe)–Mo type.

The high coercivity before 10 h of milling is attributed to strong pinning of domain walls of the interaction domains at the grain boundaries.

The Ni, Fe and Mo maps on starting sample (0 hours milling) and on the 12 hours milled sample. It can observe the chemical

homogeneity of the Supermalloy powders obtained by mechanical alloying and the particles morphology, too.

Ni particles Fe particles Mo particles



FAPASField activated pressure assisted sintering.Compared to a classical sintering process under pressure, a currentis applied in order to assist the sintering.A current exhibiting a high intensity (up to 8,000 A) under low voltage (10 V) is applied.

Spark plasma sinteringA process leading to bulk materials by a sintering step using pulse electric discharge.Due to the high intensity of the current, plasma may occur between the various powder grains.

Methods to produce from the nanocrystalline powders a a nanocrystalline compact

Soft magnetic nanocrystalline composites

Ni3Fe

polymer layer

+polymer

dissolvingNi3Fenano

covered powder (1, 1.5, 2, 3 wt%)

Die pressed (600 - 800 MPa )

Polymerisation(60 min., 180 oC)

Composites Production

I. Chicinaş, O. Isnard, O. Geoffroy, V. Pop, J. Magn. Magn. Mater. 290-291 (2005), 1531-1534

10

15

20

25

30

35

20

40

60

80

100

120

140

0 10 20 30 40 50 60

B=0.1T

µ; Ni3Fe_1_700µ; Ni3Fe_1-5_600µ; Ni3Fe_1-5_700µ; Ni3Fe_1-5_800µ; Ni3Fe_2_700µ; Ni3Fe_3_700

P/f (J/m^3); Ni3Fe_1_700P/f (J/m^3); Ni3Fe_1-5_600P/f (J/m^3); Ni3Fe_1-5_700P/f (J/m^3); Ni3Fe_1-5_800P/f (J/m^3); Ni3Fe_2_700

µ

P/f (

J/m

3 )

f (kHz)


Conclussions

The possibility of producing chemical transformations through mechanical energy has been extensively demonstrated in metallic as well as in oxide systems

The nanocrystalline/nanosized powders obtained by different mechanical routes exhibit very interesting properties, some from them different from those of bulk materials

Acknowledgements

Prof. Olivier Isnard, Laboratoire de Cristallographie, CNRS, associé à l’Université J. Fourier, Grenoble, FranceProf. Viorel Pop, Faculty of Physics, Babes-Bolyai University, Cluj-Napoca, Romania

Prof. Jean Marie Le Breton, Groupe de Physique des Matériaux, UMR CNRS 6634, Université de Rouen, France

Prof. Zeno Sparchez, Department of Materials Science and Technology, Technical University of Cluj-Napoca, Romania

Prof. Olivier Geoffroy, Laboratoire Louis Neel, CNRS, associéà l’Université J. Fourier, Grenoble, France

Thanks for your attention!

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