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ACOUSTIC EMISSION AND STRUCTURAL TRANSITIONS

ACOUSTIC EMISSION AND STRUCTURAL TRANSITIONS. Lluís Mañosa Departament d’Estructura i Constituents de la Matèria Facultat de Física lluis@ecm.ub.es. Erell Bonnot Francisco José Pérez-Reche Antoni Planes Eduard Vives. Sources of AE: Propagation of dislocations Crack growth

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ACOUSTIC EMISSION AND STRUCTURAL TRANSITIONS

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  1. ACOUSTIC EMISSION AND STRUCTURAL TRANSITIONS Lluís Mañosa Departament d’Estructura i Constituents de la Matèria Facultat de Física lluis@ecm.ub.es Erell Bonnot Francisco José Pérez-Reche Antoni Planes Eduard Vives

  2. Sources of AE: • Propagation of dislocations • Crack growth • Phase Changes • ….. 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. First EA measurements: J. Kaiser (1950)

  3. AE Fundamentals Equation of motion: (Einstein notation) along the “n” direction: for a point force The solution is the Green funcion: Uniqueness theorem + Reciprocity theorem

  4. Elastic constants Displacement field for body forces f throughout V and to boundary conditions on S

  5. V S  +  -  Discontinuities across an internal surface  much smaller thanx

  6. Usual assumption: No body forces SEISMIC MOMENT which yields:

  7. DETECTION OF AE WAVES Detectability Typically: Dislocation propagating 10m at 3000m/s 100m at 300m/s Crack area (propagating at ~ 1000 m/s) ~ 10 m2 Phase change ~ 10 m3

  8. Optical (laser), Electromagnetic, Piezoelectric ……… TRANSDUCERS Acoustic coupling Displacement Conical broad band Damped piezoelectric Piezoelectric

  9. Predicted Displacement 10-8 cm Measured S.P. Gross et al. PRL 71, 3162 (1993) Transducer calibration Breaking pencil lead (0.3mm thick)

  10. TYPES OF AE SIGNALS Burst Continuous

  11. AE Detection Ring-down counting Count rate Distributions: amplitude, duration, … RESSONANT RMS Power and energy Frequency spectrum Source characterization BROAD BAND

  12. SELECTED EXPERIMENTAL RESULTS 1. Broad band detection 2. Ressonant detection

  13. Assumptions: No body forces Far field approximation  plane (normal )  Application to martensitic transformations Ll. Mañosa, et al Appl. Phys. Lett. 54, 2574 (1989) Ll. Mañosa, et al. Acta Metall. Mater. 38 1635 (1990) Kinematics Radiation pattern (spatial information)

  14. RADIATION PATTERN Longitudinal waves Shear waves and perpendicular to KINEMATICS

  15. 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)

  16. Predicted radiation pattern EXPERIMENT: Simultaneous detection on four directions. Predominant mechanism: shear

  17. Fourier transform: Nodes at: Time domain: Convolution with a box funcion of apparent duration KINEMATICS Model: Fault with unidirectional propagation

  18.  depends on the measurement direction  DOPPLER EFFECT EXPERIMENT: Simultaneous detection at opposite faces Source location (depth, z): Fault length Fault velocity

  19. Broad-band detection: 1.- Low sensitivity, 2.- Complex experimental set-up 3.- Difficult interpretation Most studies use ressonant detection

  20. AE as a sensitive probe “Bell” sounds  Something happens!! Monitoring large structures: oil plants, rock mines, tunnels, underground caverns, etc… Detection of phase transitions Martensitic transition in Cu-Zn-Al A.Planes et al, Phys. Stat. Sol (a) 66, 717 (1981) Heat flow Acoustic emission (count rate)

  21. NUCLEATION Extreme sensitivity to small transforming volumes!! Martensitic transformation In Fe-30%Ni. J. Galligan, T. Garosshen, Nature 274, 674 (1978)

  22. MARTENSITIC TRANSFORMATION IN Cu-BASED SHAPE-MEMORY ALLOYS Step like experiments T=0.2K t=4hours Cu-Al-Ni Cu-Zn-Al ATHERMAL ISOTHERMAL Perez-Reche et al, PRL 87, 195701 (2001)

  23. EXPERIMENTS REVEALING THE ATHERMAL CHARACTER OF A PHASE TRANSITION 0.1 K/min 0.5 K/min 1 K/min 2 K/min 2.0x106 1.5x106 1.0x106 230 235 240 5.0x106 0.0 238 240 242 244 246 T (K) ____________________________________________________________ Driving rate dependence (cooling) Perez-Reche et al, PRL 87, 195701 (2001) Cu-Zn-Al Cu-Al-Ni  (Hz) /T (K-1)

  24. STATISTICAL ANALYSIS OF AE SIGNALS 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 avalanches 2.- Migration of dislocation avalanches

  25. 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) Dislocation motion in ice. MC Miguel et al. Nature 410, 667 (2001). AE from volcanic rocks P.Diodati et al. PRL 67, 2239 (1991)

  26. PHASE TRANSISIONS Martensitic transition in Cu-based shape memory alloys E. Vives et al PRL 72, 1694 (1994) Ll.Carrillo et al PRL 81, 1889 1694 (1998) Magnetostructural transition in giant magnetocaloric Gd-Si-Ge Pérez-Reche et al. PRB submitted.

  27. Transducer Dig. Osc. Preamp. Amp. Sample Cu block T Power TYPICAL AE DETECTION SYSTEM Electric signal Piezoelectric transducer (PZT) Acoustic source Peltier element

  28. DETECTION OF A.E.: EXPERIMENTAL SET-UP

  29. 1.2x105 1.2x105 n = 2 n = 150 n = 4 n = 200 n = 10 n = 300 n = 22 n = 40 8x104 8x104 4x104 4x104 0.0 0.0 220 230 240 220 230 240 T (K) T (K) Correlation n cycles RESULTS ON THE MARTENSITIC TRANSITION IN Cu-BASED ALLOYS 1. Reproducibility of the transition (mesoscale): training. Cu-Zn-Al Correlation function:

  30. Cu-Al-Mn

  31. Cu-Al-Mn

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

  33. 2. Effect of driving rate F.J. Pérez-Reche et al. PRL 93, 195701 (2004)

  34. 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

  35. 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 Techniques • in 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

  36. ECM Condensed Matter Group MICROSCOPIC MEASUREMENTS OF AVALANCHES ____________________________________________________________ Vives et al., PRL, 72, 1694 (1994) Carrillo et al. PRL, 81, 1889 (1998) Structural transition (martensitic) BCC  close packed stress- or T- driven Acoustic emission: pulse detection counting ____________________________________________________________ MULTIMAT. Kick-off Meeting. Introductory Courses. Leipzig, October 26-30 2004.

  37. Uniqueness theorem: The displacement u through the volume V with surface S is uniquely Determined after a time t0 by the initial values of displacment and particle velocity at t0, throughout V; and by values at all times tt0 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

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