Dr. Christoph Eberl

Nachwuchsgruppenleiter
Nanowissenschaft; Mikrotechnologie; Angewandte und neue Materialien
Gruppe: Gruppenleiter
Tel.: +49 721 608-22252
Fax: +49 721 608-22347
chris eberlUrx8∂kit edu
Forschung

Karlsruhe Institute of Technology (KIT)

Institute for Applied Materials

Campus North, Bldg. 696

Hermann-von-Helmholtz-Platz 1

D-76344 Eggenstein-Leopoldshafen

Germany

Microreliability

Junior Research Group of Dr. Christoph Eberl

The research of the group at the izbs and IMFII focuses on the relationship of mechanical properties and reliability of materials and their underlying microstructure on the micro- and nanoscale. Of special interest are micro molded component, coating, MEMS and thin film materials as well as bulk nanocrystalline and nanoporous metals.

Besides the interests in material science we also address challenges in experimental mechanics on this size scale by custom build setups.

Labor

Materials for micro molded components

Casting of micro-sized components for small scale applications is still a challenging subject. Therefore several instituts from the KIT and Freiburg collaborate in the Sonderforschungsbereich 499 (www.sfb499.de). This project is financed by the German Science Foundation (www.dfg.de) to further the understanding of micromolding.

Materials for thin film applications

Structured thin metal films are essential materials in modern microelectronics and their reliability can determine the applications lifetime. Therefore, we focus on the impact of the thin film microstructure on fatigue mechanisms in such materials.

Nanocrystalline materials

Nanostructured materials have shown promissing mechanical properties which will enable new applications where classical materials cannot be used. To be able to predict applications lifetime we need to understand the underlying fatigue mechanisms.

Mitglieder der Nachwuchsgruppe Dr. Christoph Eberl
Portrait	Name	E-Mail
	Kennerknecht, Tobias	tobias kennerknechtEto3∂kit edu
	Burger, Sofie	sofie burgerTqu8∂kit edu
	Funk, Matthias	matthias funkYqz7∂kit edu
	Straub, Thomas	thomas straubVsy8∂kit edu
	Bundschuh, Sven	sven bundschuhCxa1∂kit edu

Projects & Collaborations

Junior Research Group of Dr. Christoph Eberl

T.J. Balk (Univ. of Kentucky):

‘Internal Friction Measurements in Nanocrystalline Materials’,

’Mechanical Properties of Nanoporous Materials’

K. J. Hemker (JHU), D. S. Gianola (KIT), M.Y. He, S. Faulhaber, T. Evans (UCSB):

‘Mechanical properties of TBC top and bond coats’

S. P. Joshi (Uni. of Singapour), K. T. Ramesh (JHU):

‘Bimodal plastic deformation in cryo-milled and extruded Al’

O. Kraft (KIT):

‘Fatigue of Thin Films’

H. Riesch-Oppermann (KIT):

‘Statistical Modelling'

C. Schuh, T. J. Rupert (MIT):

‘Functionally Graded Coatings’

J. Schoenung (UC Davis),M. Göken (Univ. Erlangen), K.J. Hemker (Johns Hopkins University):

‘Creep properties of cryo-milled MCrAlY Bond Coat’

W. N. Sharpe (JHU):

‘Ultra High Speed Strain Measurement’

M. Wilhelm (KIT):

‘Fourier Analysis applied as Fatigue Criteria of Materials’

Digital Image Correlation and Tracking

Junior Research Group of Dr. Christoph Eberl

Digital Image Correlation and Tracking

Free MATLAB® code for DIC and DDIT is available online.

Accurate tensile testing requires direct strain measurement in the gage section of the specimen and in small-scale testing this can be achieved by non-contact strain measurement methods. Notable approaches include the interferometric strain displacement gage (see ISDG, W.N. Sharpe), tracking of diffraction spots from gratings deposited on specimen surfaces, digital image correlation (DIC), and differential digital image tracking (DDIT). These techniques also allow for the measurement of the lateral strain to measure Poisson’s ratio. Digital image correlation and DDIT have the advantage of full-field capability giving local fidelity (e.g., strain heterogeneities near grain boundaries). These techniques measure the strain even after tensile necking extending the measurable stress-strain behavior beyond the maximum engineering stress. In the case of in situ tensile testing, DIC and DDIT are ideal methods for strain measurement, as the SEM, FIB, or AFM can be used as image sources during the test. Thus, quantitative information can be extracted in addition to imaging the deformation morphology during testing.

The basic premise of DIC is as follows, and a representative image demonstrating good surface contrast on a microspecimen is shown in the Figure below. The correlation coefficients of subsets of consecutive images (typically between 10 × 10 to 40 × 40 pixels²) are calculated and plotted versus their position. Biquadratic functions, for instance, can be used to locate the maximum correlation coefficient (with sub-pixel resolution) that is representative of the optimal fit between the subsets of the two images. Differential digital image tracking requires intensity peaks in the source images that can be tracked by a peak fitting algorithm (Figure 5b). This method can achieve a resolution of up to a thousandth of a pixel, which allows for good strain fidelity even in the absence of many pixels (e.g., AFM images with ~200 × 200 pixels² resulting in strain resolutions of up to Δε = 10^–5). Ultimately, the resolution of DIC and DDIT primarily hinge on the noise present in the imaging system. Differential digital image tracking is typically less susceptible to local image noise since features are tracked that span multiple pixels.

This text is part of a review on small scale tensile testing:

http://www.tms.org/pubs/journals/JOM/0903/gianola-0903.html

Publikationen

Junior Research Group of Dr. Christoph Eberl

ISI Publikationen, C. Eberl, 2005-2011

Under Review:

C. Eberl, X. Wang, D.S. Gianola, M.Y. He, A.G. Evans, K.J. Hemker, ‘In Situ Measurement of the Toughness of the Interface Between a Thermal Barrier Coating and a Ni Alloy’, Journal of American Ceramic Society.

S. Burger, C. Eberl, A. Siegel, A. Ludwig, O. Kraft, 'A Novel High-Throughput Fatigue Testing Method for Metallic Thin Films’, Science and Technology of Advanced Materials.

Accepted:

J. Prokop, C. Eberl, M. Funk, P. Prüfe, J. Lorenz, V. Piotter, M. Welz, H.-J. Ritzhaupt-Kleissl, 'Investigation of Micro-testing samples produced by a new LiGA related process chain', Mic. Syst. Tech..

C. Eberl, D.S. Gianola, X. Wang, M.Y. He, A.G. Evans, K.J. Hemker, 'A Method for In Situ Measurement of the Elastic Behavior of a Columnar Thermal Barrier Coating', Acta Materialia.

M. Funk, K. Ma, C. Eberl, J. M. Schoenung, M. Göken, K. J. Hemker, 'High Temperature Mechanical Behavior of End-of-life Cryomilled NiCrAlY Bond Coat Materials', Met. Trans. A..

M. Funk, C. Eberl, 'Investigations on the Fatigue Behavior of Nanocrystalline Metals', Key Eng. Mat., Proc. of sixth Int. Conf. on MAT. STRUCT. & MICROMECH. OF FRACT. 2010, accepted.

S. Burger, B. Rupp, A. Ludwig, O. Kraft, C. Eberl, 'Fatigue Testing of Thin Films', Key Eng. Mat., Proc. of sixth Int. Conf. on MAT. STRUCT. & MICROMECH. OF FRACT. 2010, accepted.

2010

18. C. Eberl., T. Saif, ‘In Situ Mechanical Testing of Biological andor Inorganic Materials at the Microscale and -/Nanoscale’, Guest Ed., MRS Bullettin, 35, 5 347-350 (2010).

17. C. Eberl, H. Riesch-Oppermann, R. Spolenak, F. Kubat, W. Ruile, D. Courty, O. Kraft, ‘In situ observations and quantitative analysis of short circuit probability due to ultra high frequency fatigue’, IEEE Transactions on Device and Materials Reliability, PP, 99 (2010).

16. C. Eberl, D. S. Gianola, K. J. Hemker, ‘Mechanical characterization of coatings using microbeam bending and digital image correlation techniques’, Exp. Mech., 50, 1 (2010).

2009:

15. T. J. Balk, C. Eberl, Y. Sun, K. J. Hemker, and D. S. Gianola, ’Tensile and Compressive Microspecimen Testing of Bulk Nanoporous Gold’, JOM, 24-30, Dec (2009).

14. D. S. Gianola, C. Eberl, ‘Micro- and Nanoscale Tensile Testing of Materials’, invited overview for JOM, 24-35, March (2009).

13. S. P. Joshi, C. Eberl, B. Y. Cao, K.T. Ramesh, K. J. Hemker, ‘On the Occurrence of Portevin – Le Châtelier Instabilities in Ultrafine-Grained 5083 Aluminum Alloys’. Exp. Mech., 49, 2 207-218 (2009).

2008:

12. J. Lohmiller, C. Eberl, O. Kraft, T.J. Balk ,‘Mechanical Spectroscopy of Nanocrystalline Nickel Near Room Temperature’, Scripta Mat., 59, 4 (2008).

11. A. C. Lewis, D. van Heerden, C. Eberl, K. J. Hemker, T. P. Weihs, ‚Creep Deformation Mechanisms in Fine-Grained Niobium’, Acta Mat., 56, 13(2008).

10. A. C. Lewis, C. Eberl, K. J. Hemker, T. P. Weihs, ‚Grain Boundary Strengthening in Copper/Niobium Multilayered Foils as a Function of Temperature and Strain Rate’, JMR, 23, 2 (2008).

9. K. J. Hemker, B. G. Mendis, C. Eberl, ‘Characterizing the microstructure and mechanical behavior of two-phase NiCoCrAlY bond coat for thermal barrier systems’, Mat. Sci. Eng. A, 483-484 (2008).

8. D.S. Gianola, C. Eberl, X. M. Cheng, K. J. Hemker, ‘Stress-driven surface topography evolution in nanocrystalline Al thin films’, Adv. Mat., 20, 2 (2008).

2007:

7. C. Eberl, R. Spolenak, O. Kraft, W. Ruile, E. Arzt, ‘Fatigue damage in thin film Al interconnects at ultra high frequency: a Finite Element Analysis approach’, ‘Thin Solid Films’, 515, 6 (2007).

6. W. N. Sharpe, Jr., J. Pulskamp, D. G. Gianola, C. Eberl, R. G. Polcawich, R, J, Thompson, ‘Strain measurement of silicon dioxide microspecimens by digital image processing’, Exp. Mech., 47, 5 (2007).

2006:

5. C. Eberl, R. Spolenak, O. Kraft, F. Kubat, Werner Ruile, E. Arzt, ‘Fatigue at ultra high frequencies in Al thin films’, J. Appl. Phys., 99, 11 (2006).

4. C. Eberl, R. Spolenak, E. Arzt, F. Kubat, A. Leidl, W. Ruile, O. Kraft, ‘Ultra high-cycle fatigue in pure Al thin films and line structures’, Mat. Sci. and Eng. A, 421 (2006).

2005:

3. S. Orso, U. G. K. Wegst, C. Eberl and E. Arzt, ‘Micrometer scale tensile testing of biological attachment devices’, Adv. Mat., 18 (2005).

2. F. Kubat, W. Ruile, C. Eberl, T. Hesjedal, L. M. Reindl, ‘Qualitative and quantitative analysis of acoustomigration effects in SAW-devices’, Micro Elec. Eng., 82 (2005).

1. R. Spolenak, L. Sauter, C. Eberl, ‘Reversible orientation – biased grain growth in thin metal films induced by a focused ion beam’, Scripta Mat., 53 (2005).

Begutachtete Tagungsbeiträge:

2010:

4. J. Prokop, C. Eberl, M. Funk, J. Lorenz, P. Prüfe, V. Piotter, H. J. Ritzhaupt-Kleissl, 'Mehrkomponentenspritzgießen mit Galvanoformung als Fertigungsalternative für komplexe Mikrobauteile', 2.Industriekolloquium der Forschergruppe 702 'Mikrobauteile', Karlsruhe, 24.Juni 2010. Tag.bd. S.25-35 Erlangen : Lehrstuhl f.Kunststofftechnik, (2010) ISBN 978-3-931864-49-1.

2006:

3. W.N. Sharpe, Jr., J. Pulskamp, D.S. Gianola, C. Eberl, R. Polcawich, R. Thompson, “Strain measurements of silicon dioxide microspecimens,” Proceedings of the 2006 SEM Annual Conference, St. Louis, MO, Session 46 (2006) Paper 54.

2. W. N. Sharpe, Jr., J. Pulskamp, B. G. Mendis, C. Eberl, D. S. Gianola, R. Polcawich, and K. J. Hemker, ' Tensile Stress-Strain Curves of Gold Film', ASME Conf. Proc. 2006, 533 (2006), DOI:10.1115/IMECE2006-13290.

2005:

1. Volkert, C.A., Eberl, C., Mönig, R., Walter, M., Kraft, O., 3D analysis of microstructures by focused ion beam microscopy, Gundlach, C. [Hrsg.]. Evolution of Deformation Microstructures in 3D : Proc.of the 25th Risoe Internat.Symp.on Materials Science, Roskilde, DK, September 5-10, 2004. Roskilde : Risoe National Laboratory, S.171-86, (2005).

Dr. Christoph Eberl

Research Focus

Reliability of micro components, size effects and scaling laws in materials

05/2007

Employment and Work Experience

Head of Junior Research Group 'Microreliability', KIT, Karlsruhe, Germany

Visiting Scientist at the ‘Johns Hopkins University’, Baltimore, USA.

01/2005 – 04/2007

‘Postdoctoral Fellow’ at ‘Whiting School of Engineering’, ‘Johns Hopkins University’, Baltimore, MD, USA

05/2004 - 01/2005

Sci. Associate at the Max-Planck Institute for Metals Research, Stuttgart, Project: ‘Center of Competence for Casting and Thixoforging CCT’

05/2001 - 04/2004

Sci. Associate at the University of Stuttgart and the Max-Planck Institute for Metals Research, Stuttgart, Project: ‘Microstructural stability of Surface Acoustic Wave Frequency Filter test devices’, in cooperation with EPCOS AG

Education and Qualifications

05/2001 - 12/2004

PhD in Materials Science, University of Stuttgart and Max Planck Institute for Metals Research, Title: Fatigue of thin Al films at ultra-high frequencies

10/1995 - 03/2001

‚Diplom Ingenieur’ of Materials Science (equiv. to Master’s Degree), University of Stuttgart

Stipends and Awards

05/2009

OAP (Fellow-Inbound) Programm, National University of Singapore

08/2007

Best Poster Award, Thermal Barrier Coating Conference 2007, Irsee, Germany

11/2006 – 04/2007

Stipend awarded from the Max Planck Institute for Metals Research in Stuttgart
06/2006

Otto Hahn Medal for Young Scientists of the Max Planck Society

University Classes at the KIT

Mechanics of Microsystems, O. Kraft, C. Eberl
Size Scale Effects in Micro- and Nanostructured Systems, P. Gumbsch, D. Weygand, C. Eberl, P. Gruber, M. Dienwiebel

Other Activities at the KIT

Vice Chair of the Young Investigator Network (YIN) at KIT since 2008
Organization of KIT booth and reception at the MRS Fall Meeting 2008
Representing YIN and KIT at the GAIN conference in Boston 2008

Conference Symposium (Co)Organization and sysnergistic Activities

Org., symp. MRS Fall 2010: 'Micromechanical Systems - Materials and Devices V'

Guest Editor, MRS Bulletin, ' In Situ Mechanical Testing at the Micro-/Nanoscale' together with Taher Saif, May 2010

Org., symp. MRS Fall 2010: 'Micromechanical Systems - Materials and Devices IV'

Org., symp. ’Mechanical Behavior of Low Dimensional Materials’, Materials Science & Technology 2010, 17.-21. Oktober 2010, Houston, USA

Invited Tutor, ‘Experimental and Simulation Methods for the Study of Plasticity in Small Volumes’, MRS Fall Meeting 2009, Boston, USA

Org., symp. MRS Fall 2008: “Nano- and Micro-Scale Materials: Mechanical Properties and Behavior under Extreme Environments”

Co-organizer, symposium 'Mechanical Testing', MSE 2008, Nürnberg, Germany

Org. mini symp. 8th WCCM08: “Multiscale Mechanics of Interfaces”, Venice, Italy

Reviews for:

Science (AAAS), Scripta Materialia (Elsevier), Experimental Mechanics, Surface and Coatings Technology (Elsevier), Journal of Intelligent Material Systems and Structures (Sage), MRS Conference Proceedings

University Classes at the KIT

Mechanics of Microsystems, C. Eberl, P. Gruber

Size Scale Effects in Micro- and Nanostructured Systems, P. Gumbsch, D. Weygand, C. Eberl, P. Gruber, M. Dienwiebel

Alumni
Name	Tätigkeit	Aufgabengebiet
Dhiraj Puroshottam Jetwani	Internship	Implementation of Optical based Real Time Strain Measurement
Geoffroy Kieffer	Internship	Design of an infinitely stiff load cell
Inka Sanden		Diplomarbeit an der University of Kentucky
Jochen Lohmiller		Diplomarbeit an der University of Kentucky
Nicolas Balzer	Internship	Finite element simulations on a resonant micro-fatigue setup
Thomas König		Diplomarbeit an der University of Kentucky