ACOUSTIC EMISSION AND
STRUCTURAL TRANSITIONS
Lluís Mañosa
Departament d’Estructura i Constituents de la MatèriaFacultat de Fí[email protected]
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