Residual stress measurement in thin films using the semi-destructive ring-core drilling method using Focused Ion Beam

Recently, a new method for residual stress measurement in thin films by using the focused ion beam (FIB) has been proposed by the authors. It is based on the combined capability of the FIB imaging system and of high-resolution strain mapping software (VIC-2D). A simple equation based on two-dimensional elasticity is used to evaluate the residual stress from the displacements due to introducing a slot. The slot length is assumed to be much larger than the slot width or depth. And the effect of the slot width was neglected. However, it is often hard, depending on film materials, to introduce a narrow and deep slot by FIB. In this work some practical issues regarding the slot geometry are addressed. Through two- and three-dimensional finite element analyses, it is explored how the slot length, width and measurement location affect the displacements which are the basic data for residual stress evaluation. As a result, the validity and limit of the equations based on two-dimensional elasticity are evaluated. Also, the effect of material dissimilarity between film and substrate is explored. Finally, examples for a diamond-like carbon film on glass substrate and an aluminum oxide film thermally grown upon an alloy are presented.

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DIC Image on FIB Ring-Core Analysis of Depth Sensing Residual Stress Measurement of Thin Films

Conference Proceedings of the Society for Experimental Mechanics Series - Advancement of Optical Methods & Digital Image Correlation in Experimental Mechanics, Volume 3 ◽

10.1007/978-3-319-97481-1_15 ◽

2018 ◽

pp. 109-111 ◽

Cited By ~ 1

Author(s):

Wen Chieh Pan ◽

Ang-Ting Tsai ◽

Fa-Yen Cheng ◽

Terry Yuan-Fang Chen ◽

Ming-Tzer Lin

Keyword(s):

Thin Films ◽

Residual Stress ◽

Stress Measurement ◽

Residual Stress Measurement ◽

Core Analysis ◽

Depth Sensing ◽

Ring Core

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Intragranular Residual Stress Evaluation Using the Semi-Destructive FIB-DIC Ring-Core Drilling Method

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.996.8 ◽

2014 ◽

Vol 996 ◽

pp. 8-13 ◽

Cited By ~ 8

Author(s):

Alexander J.G. Lunt ◽

Alexander M. Korsunsky

Keyword(s):

Residual Stress ◽

Residual Stresses ◽

Titanium Aluminide ◽

Ion Beam ◽

Sample Surface ◽

Image Correlation ◽

Near Surface ◽

Core Drilling ◽

Drilling Method ◽

Ring Core

Titanium aluminide (TiAl) is a lightweight intermetallic compound with a range of exceptional mid-to-high temperature mechanical properties. These characteristics have the potential to deliver significant weight savings in aero engine components. However, the relatively low ductility of TiAl requires improved understanding of the relationship between manufacturing processes and residual stresses in order to expand the use of such components in service. Previous studies have suggested that stress determination at high spatial resolution is necessary to achieve better insight. The present paper reports progress beyond the current state-of-the-art towards the identification of the near-surface intragranular residual stress state in cast and ground TiAl at a resolution better than 5μm. The semi-destructive ring-core drilling method using Focused Ion Beam (FIB) and Digital Image Correlation (DIC) was used for in-plane residual stress estimation in ten grains at the sample surface. The nature of the locally observed strain reliefs suggests that tensile residual stresses may have been induced in some grains by the unidirectional grinding process applied to the surface.

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