TY - JOUR

T1 - Combined X-ray microdiffraction and micromechanical testing for direct measurement of thin film elastic constants

AU - Janknecht, Rebecca

AU - Hahn, Rainer

AU - Koutná, Nikola

AU - Todt, Juraj

AU - Meindlhumer, Michael

AU - Davydok, Anton

AU - Riedl, Helmut

AU - Keckes, Jozef

AU - Mayrhofer, Paul Heinz

PY - 2025/4

Y1 - 2025/4

N2 - Direct measurement of elastic constants for thin films is still far from routine and poses significant technical and analytical challenges compared to bulk materials. Ab initio Density Functional Theory calculations offer theoretical input, however, discrepancies between model systems and real-world properties persist, primarily due to a lack of available experimental data for newly emerging material systems. Moreover, computationally affordable models are typically limited to defect-free single crystals, omitting microstructural effects that strongly influence the material’s behavior. This study addresses this gap by proposing a novel experimental approach to measure direction-dependent elastic constants, combining synchrotron microdiffraction and micropillar compression, testing a polycrystalline face-centered cubic TiN0.8B0.2 thin film, where linear elastic failure prevails. We have established an advanced in-situ testing environment to continuously record the load–displacement of the indenter while simultaneously collecting the material’s deformation response to uniform uniaxial compression. This dynamic approach allows the evaluation of the orientation-dependent elastic strain components and the macroscopic uniaxial compressive stresses, each over time, enabling a differential analysis to assess the elastic and X-ray elastic constants. The excellent agreement between experimental and ab initio data solidifies the here-proposed robust method for direct elastic constant measurements, which is crucial for advancements in thin film material testing.

AB - Direct measurement of elastic constants for thin films is still far from routine and poses significant technical and analytical challenges compared to bulk materials. Ab initio Density Functional Theory calculations offer theoretical input, however, discrepancies between model systems and real-world properties persist, primarily due to a lack of available experimental data for newly emerging material systems. Moreover, computationally affordable models are typically limited to defect-free single crystals, omitting microstructural effects that strongly influence the material’s behavior. This study addresses this gap by proposing a novel experimental approach to measure direction-dependent elastic constants, combining synchrotron microdiffraction and micropillar compression, testing a polycrystalline face-centered cubic TiN0.8B0.2 thin film, where linear elastic failure prevails. We have established an advanced in-situ testing environment to continuously record the load–displacement of the indenter while simultaneously collecting the material’s deformation response to uniform uniaxial compression. This dynamic approach allows the evaluation of the orientation-dependent elastic strain components and the macroscopic uniaxial compressive stresses, each over time, enabling a differential analysis to assess the elastic and X-ray elastic constants. The excellent agreement between experimental and ab initio data solidifies the here-proposed robust method for direct elastic constant measurements, which is crucial for advancements in thin film material testing.

KW - Mechanical properties testing

KW - Synchrotron diffraction

KW - Elastic constants

KW - Density Functional Theory (DFT)

KW - stress and strain

U2 - 10.1016/j.matdes.2025.113720

DO - 10.1016/j.matdes.2025.113720

M3 - Article

VL - 2025

JO - Materials and Design

JF - Materials and Design

SN - 0264-1275

IS - 252

M1 - 113720

ER -