Project Description

Indentation methods are commonly used to assess local mechanical properties because of their speed and minimal sample preparation, making them well suited to input into machine learning approaches to materials discovery. However, fracture and toughness are not commonly assessed with indentation in metallic materials which suffer from hydrogen embrittlement. With the increasing use of hydrogen in the energy and materials processing landscape, addressing this gap is timely, and likely to lead to high visibility results for a researcher that can develop the next “Rockwell” or “Charpy” test. To design the new high throughput test the successful post-doc will create finite element simulations of novel indentation tip geometries using multiscale approaches. These simulations will predict the regions of tension on the surface of the sample, providing a toughness analog when measurable cracking occurs. The candidate will perform experimental testing on electrochemically charged steel systems, characterize microstructural features that may dominate the compare model predictions to experimental data, and carry out these experiments in situ during charging, post charging, and as a function of temperature to identify shifts in ductile/brittle transition temperatures.

Start Date

Spring semester 2025 

Postdoc Qualifications

Experience with mechanical engineering simulation tools (mechanics, plasticity, transport).
Experimental characterization of materials experience

Co-advisors

David Bahr, dfbahr@purdue.edu, School of Materials Engineering
Marisol Koslowski, marisol@purdue.edu, School of Mechanical Engineering 

Bibliography

Hydrogen effects on dislocation activity in austenitic stainless steel, K.A. Nibur, D.F. Bahr, and B.P. Somerday, Acta Materialia, vol. 54, pp. 2677-2684 (2006).

Probing the effect of hydrogen on elastic properties and plastic deformation in nickel using nanoindentation and ultrasonic methods, S.K. Lawrence, B.P. Somerday, M.D. Ingraham, D.F. Bahr, JOM, vol. 70, pp. 1068-1073 (2018)

Hydrogen charging can relax compressive residual stresses caused by shot peening, Jia-Huei Tien, Megan Regar, David R. Johnson, and David F. Bahr, International Journal of Hydrogen Energy, https://doi.org/10.1016/j.ijhydene.2024.06.215

Corrosion-induced fracture of Cu–Al microelectronics interconnects, Kai-chieh Chiang and Marisol Koslowski, Modelling and Simulation in Materials Science and Engineering, 32, 045004, 2024.

Stacking fault fluctuation effects on the strengthening of high entropy alloys, Yifei Zeng, Xiaorong Cai, and Marisol Koslowski, Acta Materialia, 164 1-11, 2019