Room temperature mechanical behaviour of a Ni-Fe multilayered material with modulated grain size distribution

Abstract

To gain fundamental insight into the relationship between length scales and mechanical behaviour, Ni-Fe multilayered materials with a 5-μm-layer thickness and a modulated grain size distribution have been synthesized by pulsed electrodeposition. Microstructural studies by SEM and TEM reveal the alternating growth of well-defined layers with either nano (d = 16 nm) or coarse grains (d ≥ 500 nm). Room temperature tensile tests have been performed to investigate the mechanical response and understand the underlying deformation mechanisms. Tensile test results and fractographic studies demonstrate that the overall room temperature mechanical behaviour of the multilayered material, i.e. strength and ductility, is governed primarily by the layers containing nanocrystalline grains. The measured properties have been discussed in the context of modulated grain structure of the multilayered sample and contribution of each grain size regime to the overall strength and ductility.

Keywords:

• Ni-Fe
• electrodeposition
• multilayered structure
• tensile test

Acknowledgements

The authors are grateful to Dr Troy Topping for the help in EDM machining of tensile samples, Dr Jochen Fiebig and Mr Josh Yee for the help with SEM and acquiring EBSD map. LK would like to acknowledge Dr Yulia Ivanisenko (KIT, Karlsruhe, Germany) for the opportunity to use tensile machine.

Additional information

Funding

Funding. Financial support from Office of Naval Research under grants N00014-13-1-0557 (Research at UCD), N00014-13-1-0555 (TEM work at Texas A&M University), and N00014-10-C-0371 (Sample preparation at Integran Technologies Inc) with Dr Lawrence Kabacoff as the program manager are gratefully acknowledged.