Microstructure-dependent deformation behaviour of bcc-metals - indentation size effect and strain rate sensitivity

Maier V, Schunk C, Göken M, Durst K (2015)

Publication Status: Published

Publication Type: Journal article

Publication year: 2015

Journal

Philosophical Magazine Taylor & Francis: STM, Behavioural Science and Public Health Titles / Taylor & Francis

Publisher: TAYLOR & FRANCIS LTD

Book Volume: 95

Pages Range: 1766-1779

Journal Issue: 16-18

DOI: 10.1080/14786435.2014.982741

Abstract

In this work, the indentation size effect and the influence of the microstructure on the time-dependent deformation behaviour of body-centred cubic (bcc) metals are studied by performing nanoindentation strain rate jump tests at room temperature. During these experiments, the strain rate is abruptly changed, and from the resulting hardness difference the local strain rate sensitivity has been derived. Single-crystalline materials exhibit a strong indentation size effect; ultrafine-grained metals have nearly a depth-independent hardness. Tungsten as a bcc metal shows the opposite behaviour as generally found for face-centered cubic metals. While for UFG-W only slightly enhanced strain rate sensitivity was observed, SX-W exhibits a pronounced influence of the strain rate on the resulting hardness at room temperature. This is due to the effects of the high lattice friction of bcc metals at low temperatures, where the thermally activated motion of screw dislocations is the dominating deformation mechanisms, which causes the enhanced strain rate sensitivity. For the SX-materials, it was found that the degree of the indentation size effect directly correlates with the homologous testing temperature and thus, the material specific parameter of the critical temperature T-c. However, for the resultant strain rate sensitivity no depth-dependent change was found.

Authors with CRIS profile

Christopher Schunk Lehrstuhl für Werkstoffwissenschaften (Allgemeine Werkstoffeigenschaften) Mathias Göken Lehrstuhl für Werkstoffwissenschaften (Allgemeine Werkstoffeigenschaften) Karsten Durst Lehrstuhl für Werkstoffwissenschaften (Allgemeine Werkstoffeigenschaften)

Additional Organisation(s)

Exzellenz-Cluster Engineering of Advanced Materials Lehrstuhl für Werkstoffwissenschaften (Allgemeine Werkstoffeigenschaften)

Related research project(s)

In-situ nanomechanics and FIB tomography of thin films (EXC315 EAM (A2-3)) Exzellenz-Cluster Engineering of Advanced Materials Nov. 1, 2012 - Oct. 31, 2017

Involved external institutions

Montanuniversität Leoben AT Austria (AT)

How to cite

APA:

Maier, V., Schunk, C., Göken, M., & Durst, K. (2015). Microstructure-dependent deformation behaviour of bcc-metals - indentation size effect and strain rate sensitivity. Philosophical Magazine, 95(16-18), 1766-1779. https://dx.doi.org/10.1080/14786435.2014.982741

MLA:

Maier, Verena, et al. "Microstructure-dependent deformation behaviour of bcc-metals - indentation size effect and strain rate sensitivity." Philosophical Magazine 95.16-18 (2015): 1766-1779.

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