"Nanomechanical Testing of Strong Solids at High Temperatures"
The general objective of this project is the development of micromechanical characterization techniques at high temperature for the study of strong nanoscale multilayered materials. Micropillar compression at room temperature has been proven an effective method to probe size effecs in metals. The main hypothesis that supports this proposal is that this method is suitable for testing the deformation and fracture mechanisms of complex strong solids, with negligible size effects, in a wide range of temperatures and strain rates, to obtain the constitutive behaviour of single phases and/or single grains of the bulk material at different orientations. We now have enough evidence to support this hypothesis together with the advanced scientific equipment required to perform the work. There are several reasons to use this approach: (1) This new capability will open the door to get a better understanding of the deformation and fracture micromechanisms in complex microstructures containing multiple phases and interfaces, like in fully lamellar TiAl alloys; (2) In many cases, the available amount of material does not allow to use conventional bulk testing and new micromechanical methods are required, like in nanoscale multilayers. And (3), the material properties obtained at the microscale can be used to predict the macroscopic response of polycrystalline aggregates of nanolayered grains, using multiscale modelling techniques. To prove this, the approach will be applied to two nanolayered material systems of technological relevance: fully lamellar TiAl intermetallics and nanoscale multilayers. The technique can shed valuable information regarding the macroscopic mechanical behavior of these materials that is difficult to obtain using conventional bulk testing or in-situ testing techniques, like the strength as a function of the layer spacing and the layer orientation in a wide range of temperatures. This knowledge, together with the aid of multiscale modelling, will contribute strongly to the optimization of the microstructure of these materials.
Funding Organization: Spanish Ministry of Economy and Competitiveness (Fundamental Research)
Project Period: 2013 – 2016
Principal Investigator: Dr. Jon Molina