Displacement-controlled nanoindentation stress relaxation tests for reliable determination of activation volumes

Suprit P. Bhusare; Aloshious Lambai; Jakob Schwiedrzik; Johann Michler; Brad L. Boyce; Gaurav Mohanty

doi:10.1016/j.matdes.2025.115067

Displacement-controlled nanoindentation stress relaxation tests for reliable determination of activation volumes

Suprit P. Bhusare^*
, Aloshious Lambai
, Jakob Schwiedrzik
, Johann Michler
, Brad L. Boyce
, Gaurav Mohanty

^*Corresponding author for this work

Not published at VTT

Tampere University

Research output: Contribution to journal › Article › Scientific › peer-review

Abstract

This study presents the development of nanoindentation stress relaxation testing as a robust method for extracting deformation activation parameters in materials. Using an in-situ, displacement-controlled nanoindenter, stress relaxation tests were conducted on nanocrystalline (nc) nickel (Ni) with Berkovich, cube-corner, and spherical tips. Results showed good agreement with uniaxial micropillar compression relaxation tests performed on the same sample, demonstrating the reliability of the testing protocol and data analysis methodology. The apparent and effective activation volumes were comparable, indicating minimal changes in deformation substructure during indentation relaxation. Effective activation volumes averaged 8.11 ± 3.3 b3 for indentation and 5.91 ± 0.8 b3 for micropillar compression, with corresponding strain rate sensitivity exponents (m) of 0.028 ± 0.002 and 0.028 ± 0.001, respectively. These consistent values underscore the reliability of the indentation-based approach for probing transient plasticity. Additional tests on single-crystal (sx) Ni and chromium (Cr) revealed strong and weak strain dependence of activation volume, respectively. Overall, this work establishes nanoindentation stress relaxation as a promising technique for investigating size effects and transient plasticity mechanisms in metals.

Original language	English
Article number	115067
Journal	Materials and Design
Volume	260
DOIs	https://doi.org/10.1016/j.matdes.2025.115067
Publication status	Published - Dec 2025
MoE publication type	A1 Journal article-refereed

Funding

G.M. and S.P.B. acknowledge funding from Research Council of Finland grant no. 341050. S.P.B. also acknowledges funding from Jenny and Antti Wihuri Foundation grant number 00240029 and Finnish Cultural Foundation grant number 50251175. This work has used the facilities of Tampere Microscopy Center (TMC), Tampere, Finland. BLB was supported by the DOE Office of Basic Energy Sciences, Department of Materials Science and Engineering.

Keywords

Activation parameters
Activation volume
Deformation mechanisms
Nanocrystalline metals
Nanoindentation stress relaxation
Transient testing

Access to Document

10.1016/j.matdes.2025.115067Licence: CC BY

Cite this

@article{9d96d24e206b480c98c660d9a4a6ceac,

title = "Displacement-controlled nanoindentation stress relaxation tests for reliable determination of activation volumes",

abstract = "This study presents the development of nanoindentation stress relaxation testing as a robust method for extracting deformation activation parameters in materials. Using an in-situ, displacement-controlled nanoindenter, stress relaxation tests were conducted on nanocrystalline (nc) nickel (Ni) with Berkovich, cube-corner, and spherical tips. Results showed good agreement with uniaxial micropillar compression relaxation tests performed on the same sample, demonstrating the reliability of the testing protocol and data analysis methodology. The apparent and effective activation volumes were comparable, indicating minimal changes in deformation substructure during indentation relaxation. Effective activation volumes averaged 8.11 ± 3.3 b3 for indentation and 5.91 ± 0.8 b3 for micropillar compression, with corresponding strain rate sensitivity exponents (m) of 0.028 ± 0.002 and 0.028 ± 0.001, respectively. These consistent values underscore the reliability of the indentation-based approach for probing transient plasticity. Additional tests on single-crystal (sx) Ni and chromium (Cr) revealed strong and weak strain dependence of activation volume, respectively. Overall, this work establishes nanoindentation stress relaxation as a promising technique for investigating size effects and transient plasticity mechanisms in metals.",

keywords = "Activation parameters, Activation volume, Deformation mechanisms, Nanocrystalline metals, Nanoindentation stress relaxation, Transient testing",

author = "Bhusare, \{Suprit P.\} and Aloshious Lambai and Jakob Schwiedrzik and Johann Michler and Boyce, \{Brad L.\} and Gaurav Mohanty",

note = "Publisher Copyright: {\textcopyright} 2025 The Authors.",

year = "2025",

month = dec,

doi = "10.1016/j.matdes.2025.115067",

language = "English",

volume = "260",

journal = "Materials and Design",

issn = "0264-1275",

publisher = "Elsevier",

}

TY - JOUR

T1 - Displacement-controlled nanoindentation stress relaxation tests for reliable determination of activation volumes

AU - Bhusare, Suprit P.

AU - Lambai, Aloshious

AU - Schwiedrzik, Jakob

AU - Michler, Johann

AU - Boyce, Brad L.

AU - Mohanty, Gaurav

PY - 2025/12

Y1 - 2025/12

N2 - This study presents the development of nanoindentation stress relaxation testing as a robust method for extracting deformation activation parameters in materials. Using an in-situ, displacement-controlled nanoindenter, stress relaxation tests were conducted on nanocrystalline (nc) nickel (Ni) with Berkovich, cube-corner, and spherical tips. Results showed good agreement with uniaxial micropillar compression relaxation tests performed on the same sample, demonstrating the reliability of the testing protocol and data analysis methodology. The apparent and effective activation volumes were comparable, indicating minimal changes in deformation substructure during indentation relaxation. Effective activation volumes averaged 8.11 ± 3.3 b3 for indentation and 5.91 ± 0.8 b3 for micropillar compression, with corresponding strain rate sensitivity exponents (m) of 0.028 ± 0.002 and 0.028 ± 0.001, respectively. These consistent values underscore the reliability of the indentation-based approach for probing transient plasticity. Additional tests on single-crystal (sx) Ni and chromium (Cr) revealed strong and weak strain dependence of activation volume, respectively. Overall, this work establishes nanoindentation stress relaxation as a promising technique for investigating size effects and transient plasticity mechanisms in metals.

AB - This study presents the development of nanoindentation stress relaxation testing as a robust method for extracting deformation activation parameters in materials. Using an in-situ, displacement-controlled nanoindenter, stress relaxation tests were conducted on nanocrystalline (nc) nickel (Ni) with Berkovich, cube-corner, and spherical tips. Results showed good agreement with uniaxial micropillar compression relaxation tests performed on the same sample, demonstrating the reliability of the testing protocol and data analysis methodology. The apparent and effective activation volumes were comparable, indicating minimal changes in deformation substructure during indentation relaxation. Effective activation volumes averaged 8.11 ± 3.3 b3 for indentation and 5.91 ± 0.8 b3 for micropillar compression, with corresponding strain rate sensitivity exponents (m) of 0.028 ± 0.002 and 0.028 ± 0.001, respectively. These consistent values underscore the reliability of the indentation-based approach for probing transient plasticity. Additional tests on single-crystal (sx) Ni and chromium (Cr) revealed strong and weak strain dependence of activation volume, respectively. Overall, this work establishes nanoindentation stress relaxation as a promising technique for investigating size effects and transient plasticity mechanisms in metals.

KW - Activation parameters

KW - Activation volume

KW - Deformation mechanisms

KW - Nanocrystalline metals

KW - Nanoindentation stress relaxation

KW - Transient testing

UR - https://www.scopus.com/pages/publications/105021087315

U2 - 10.1016/j.matdes.2025.115067

DO - 10.1016/j.matdes.2025.115067

M3 - Article

SN - 0264-1275

VL - 260

JO - Materials and Design

JF - Materials and Design

M1 - 115067

ER -

Displacement-controlled nanoindentation stress relaxation tests for reliable determination of activation volumes

Abstract

Funding

Keywords

Access to Document

Other files and links

Fingerprint

Cite this