The Benefits of Micro-Tensile Testing vs Bulk Tensile Testing

Bulk tensile testing is often used to measure a material’s elastic modulus, fracture-, yield- and ultimate-strength. Whilst bulk testing gives useful quantitative information on the overall mechanical properties of a sample it does not take separate the effect of individual phases and interfaces within the material.

Micro-tensile testing can be used to quantify the mechanical properties of individual interfaces or phases within a material, as demonstrated in the below image. In addition, measurements on the microscale can be used to detect and investigate single plastic deformation mechanisms.

Samples are prepared for micro-tensile testing by the use of a FIB to produce a dog-bone shaped sample of uniform cross-section that stays attached to the original substrate. It is also possible to use FIB to produce a griper shape into the silicon-based force-sensing probe’s tip. The tip’s griper shape allows it to interlock with the sample’s dog bone structure to carry out of micro-tensile testing.

During tensile testing, linear elasticity is seen during the initial loading, followed by yielding, plasticity and then fracture.

True displacement-controlled testing is required to ensure that the full stress-strain curve is measured. This means that the behavior of the material following its ultimate strength, with a decreasing stress-strain curve gradient can be chosen.

Using this method of micro-tensile testing alongside the deposition of line markers or speckles along the sample (as shown) and digital image correlation (DUIC) it is possible to determine localized strain along the axis of the sample.

This information has been sourced, reviewed and adapted from materials provided by FemtoTools AG.

For more information on this source, please visit FemtoTools AG.