ACOUSTIC EMISSION AND

STRUCTURAL TRANSITIONS

Lluís Mañosa

Departament d’Estructura i Constituents de la MatèriaFacultat de Físicalluis@ecm.ub.es

Erell BonnotFrancisco José Pérez-RecheAntoni PlanesEduard Vives

Acoustic Emission (AE):

“Transient elastic waves resulting from localized internal microdisplacements taking place in a solid” (American Society for Testing and Materials, ASTM) .

Technique to measure these elastic waves.

Sources of AE:

•Propagation of dislocations•Crack growth•Phase Changes•…..

First EA measurements: J. Kaiser (1950)

AE Fundamentals

Equation of motion:

for a point force

The solution is the Green funcion:

along the “n” direction:

Uniqueness theorem

+

Reciprocity theorem

(Einstein notation)

Displacement field for body forces f throughout V and to boundary conditions on S

Elastic constants

Discontinuities across an internal surface

+-

V S

much smaller than x

SEISMIC MOMENT

Usual assumption:

which yields:

No body forces

DETECTION OF AE WAVES

Detectability

Typically: Dislocation propagating 10m at 3000m/s100m at 300m/s

Crack area (propagating at ~ 1000 m/s) ~ 10 m2

Phase change ~ 10 m3

TRANSDUCERS

Displacement

Conical broad band

Damped piezoelectric

Piezoelectric

Optical (laser),Electromagnetic,Piezoelectric………

Acoustic coupling

Transducer calibration

Breaking pencil lead(0.3mm thick)Predicted

Measured

S.P. Gross et al. PRL 71, 3162 (1993)

Dis

plac

emen

t 10-8

cm

TYPES OF AE SIGNALS

Burst

Continuous

AE Detection

Ring-down countingCount rate

Distributions: amplitude, duration, …

RMS Power and energy

Frequency spectrum

Source characterization

BR

OA

D B

AN

DR

ES

SO

NA

NT

0 50 100-0,4

-0,2

0,0

0,2

0,4

tava

t (s) V

(V

)

A

count number: I = 7acoustic activity: = 150 kHz

SELECTED EXPERIMENTAL RESULTS

1. Broad band detection

2. Ressonant detection

Application to martensitic transformations

Ll. Mañosa, et al Appl. Phys. Lett. 54, 2574 (1989)Ll. Mañosa, et al. Acta Metall. Mater. 38 1635 (1990)

Radiation pattern(spatial information)

Kinematics

Assumptions: No body forcesFar field approximation

plane (normal )

RADIATION PATTERN

KINEMATICS

Longitudinal waves

Shear waves

perpendicular toand

Thermoelastic martensitic transformation

Only longitudinal waves

Cubic single crystal (Cu-Zn-Al) with faces parallel to (111), (-102) and (2-31) planes

Trained activated martensite variant: (011)<0-1 1>

Shear mechanism: = (0,1,1) ; n=(0,-1,1)

Volume mechanism: = (0,1,1) ; n=(0,1,1)

EXPERIMENT:Simultaneous detection onfour directions.

Predicted radiation pattern

Predominant mechanism: shear

KINEMATICS

Model: Fault with unidirectional propagation

Time domain: Convolution with a box funcion of apparent duration

Fourier transform:

Nodes at:

depends on the measurement direction

DOPPLER EFFECT

EXPERIMENT: Simultaneous detection at opposite faces

Source location (depth, z):

Fault length

Fault velocity

Broad-band detection:

1.- Low sensitivity,2.- Complex experimental set-up3.- Difficult interpretation

Most studies use ressonant detection

AE as a sensitive probe

“Bell” sounds Something happens!!

Monitoring large structures: oil plants, rock mines, tunnels, undergroundcaverns, etc…

Detection of phase transitions

Heat flow

Acoustic emission(count rate)

Martensitic transition in Cu-Zn-Al

A.Planes et al,Phys. Stat. Sol (a) 66, 717 (1981)

NUCLEATION

Extreme sensitivity to small transforming volumes!!

Martensitic transformationIn Fe-30%Ni.J. Galligan, T. Garosshen,Nature 274, 674 (1978)

MARTENSITIC TRANSFORMATIONIN Cu-BASED SHAPE-MEMORY ALLOYS

-2 0 2 4 6 8 10 12 14

0

400

800

1200

t(h)

(H

z)

241.0

241.5

242.0

T(K

)

0 2 4

0

400

800

1200

252

254

256

0.0 0.10

500

1000

254.0

254.2

254.4

t (h)

T(K

)

(H

z)

Cu-Zn-Al Cu-Al-NiStep like experiments T=0.2K t=4hours

ATHERMAL ISOTHERMALPerez-Reche et al, PRL 87, 195701 (2001)

____________________________________________________________

EXPERIMENTS REVEALING THE ATHERMAL CHARACTEROF A PHASE TRANSITION

Driving rate dependence (cooling)

238 240 242 244 246

0.0

5.0x106

1.0x106

1.5x106

2.0x106

T (K)

230 235 240

0.1 K/min0.5 K/min

1 K/min 2 K/min

220 230 240 250 260

0.0

4.0x105

8.0x105

1.2x106

1.6x106

2.0x106

=0.1 K/min =0.5 K/min =1 K/min =2 K/min =5 K/min

(K

-1)

T (K)

0.0

2.0x104

4.0x104

6.0x104

(Hz)

248 2520.0

4.0x104

8.0x104

/T (

K-1)

(Hz)

Cu-Al-NiCu-Zn-Al

Perez-Reche et al, PRL 87, 195701 (2001)

Source location

Creep deformation of ice (J. Weiss, D. Marsan, Science 299, 80 (2003))

Experiment: 5 piezoelectric transucers frozen on an ice crystal subjected to uniaxial load.

1.- Clustering of dislocation avalanches2.- Migration of dislocation avalanches

STATISTICAL ANALYSIS OF AE SIGNALS

STATISTICAL ANALYSIS OF AE SIGNALS

Fracture by H precipitation in Nb

G. Cannelli et al. PRL 70, 3923 (1993) AE from paper fracture

L.I Salminen et al. PRL 89,185503 (2002)

AE from volcanic rocks

P.Diodati et al. PRL 67, 2239 (1991) Dislocation motion in ice.

MC Miguel et al. Nature 410, 667 (2001).

PHASE TRANSISIONS

E. Vives et alPRL 72, 1694 (1994) Ll.Carrillo et al

PRL 81, 1889 1694 (1998)

Martensitic transition in Cu-based shape memory alloys

Magnetostructural transition in giant magnetocaloric Gd-Si-GePérez-Reche et al. PRB submitted.

TYPICAL AE DETECTION SYSTEM

Peltier element

Preamp

.Amp. Dig. Osc.

T

Power

Cu block

Sample

Transducer

Electric signal

Piezoelectric transducer (PZT)

Acoustic source

DETECTION OF A.E.: EXPERIMENTAL SET-UP

RESULTS ON THE MARTENSITIC TRANSITIONIN Cu-BASED ALLOYS

1. Reproducibility of the transition (mesoscale): training.

220 230 240

n = 2 n = 4 n = 10 n = 22 n = 40

T (K)220 230 240

0.0

4x104

8x104

1.2x105 n = 150 n = 200 n = 300

T (K)

1.2x105

8x104

4x104

0.0

Cu-Zn-Al

Correlation function:

0 100 200 3000.90

0.92

0.94

0.96

0.98

1.00

n,n+

1

n

0 10 20 30 40 50 60

-10

-8

-6

n

ln(d

/dn)

Co

rre

latio

n

n cycles

Cu-Al-Mn

Cu-Al-Mn

REPRODUCIBILITY(microscale

C. Picornell et al.Thermochim. Acta 113, 171 (1987)

2. Effect of driving rate

F.J. Pérez-Reche et al. PRL 93, 195701 (2004)

SUMMARY

AE: very sensitive and powerful technique for fast motion

Microscopic information: spatial and temporal

Adequate to follow nucleation and kinetics of phase (structural) transitions

Particularly suitable to study avalanche-mediated processes

Selected references:

J.A. Hudson, The Excitation and propagation of elastic waves, Cambridge Univ. Press (1980).

K. Aki, P.G. Richards, Quantitative Seismology, W.H. Freeman and Company (1980).

C.B. Scruby, Quantitative Acoustic emission techniques, in Research Techniquesin Nondestructive Testing, Vol III, Ed. By R.S. Sharpe, Academic Press, 1985.

Acoustic emission – Beyond the Millennium, Ed. T. Kishi, M. Ohtsu, S. Yuyama, Elsevier (2000).

C.B. Scruby, J. Phys. E: Sci. Instrum. 20, 946 (1987).

Nondestructive testing techniques, Ed. D.E. Bray and D. McBride, John Wiley and Sons, INC (1992).

THANKS for the attention

____________________________________________________________

____________________________________________________________

MULTIMAT. Kick-off Meeting. Introductory Courses. Leipzig, October 26-30 2004.

MICROSCOPIC MEASUREMENTS OF AVALANCHES

254 256

0

5x105

1x106

220 240 260

0

1x106

2x106

3x106

Aco

ustic

act

ivity

T (K)

Structural transition (martensitic)

BCC close packed

stress- or T- driven

Acoustic emission: pulse detection

counting

Vives et al., PRL, 72, 1694 (1994)

Carrillo et al. PRL, 81, 1889 (1998)

Uniqueness theorem: The displacement u through the volume V with surface S is uniquelyDetermined after a time t0 by the initial values of displacment and particle velocity at t0, throughoutV; and by values at all times tt0 of (i) the body forces f and the heat supplied throughout V; (ii) the tractions T over any part S1 of S; and (iii) the displacement over the remainder S2 of S,with S1+S2=S