Al/SiC nanolaminates with equal nominal thicknesses of the Al and SiC layers (10, 25, 50 and 100 nm) were manufactured by magnetron sputtering. The mechanical properties were measured at 25 °C and 100 °C by means of nanoindentation and micropillar compression tests and the deformation mechanisms were analyzed by in situ micropillar compression tests in the transmission electron microscope. In addition, finite element simulations of both tests were carried out to ascertain the role played by the strength of the Al layers and by the elastic constraint of the ceramic layers on the plastic flow of Al in the mechanical response. It was found that the mechanical response was mainly controlled by the constraint during nanoindentation or micropillar compression tests of very thin layered (≈10 nm) laminates, while the influence of the strength of Al layers was not as critical. This behavior was reversed, however, for thick layered laminates (100 nm). These mechanisms point to the different effects of layer thickness during nanoindentation and micropillar compression, at both temperatures, and showed the critical role played by constraint on the mechanical response of nanolaminates made of materials with a very large difference in the elasto-plastic properties.
Bibliographical noteFunding Information:
This investigation was supported by the U.S. National Science Foundation and the Spanish Ministry of Economy and Competitiveness under the Materials World Network Program through the project “High temperature mechanical behavior of metal/ceramic nanolaminate composites” (Dr. Lynnette Madsen, NSF-DMR-1209988 , PCIN-2013-029 and MAT2012-31889 ). The nanolaminate deposition work at LANL was supported by US DOE, Office of Basic Energy Sciences . The financial support from the China Scholarship Council (CSC) (LWY) and of the Spanish Ministry of Education and the Fulbright program (JMMA) is also gratefully acknowledged. This work was performed, in part, at the Center for Integrated Nanotechnologies, an Office of Science User Facility operated for the U.S. Department of Energy (DOE) Office of Science by Los Alamos National Laboratory (Contract DE-AC52-06NA25396 ). The use of the TEM facilities at the Centro Nacional de Microscopía Electrónica (ICTS-CNME) are also gratefully acknowledged.
- Micropillar compression