Microstructural size effects on mechanical properties of high purity nickel

in International Journal of Plasticity (2011), 27

The aim of this article is to provide experimental results in order to understand the microstructural size effects which occur with a decrease in the thickness of polycrystalline nickel samples from 3.2 ... [more ▼]

The aim of this article is to provide experimental results in order to understand the microstructural size effects which occur with a decrease in the thickness of polycrystalline nickel samples from 3.2 mm to 12.5 lm. The influence of the thickness, grain size and ratio thickness to grain size on the mechanical properties and strain hardening were investigated by mechanical tests and TEM observations. The results show the presence of three different domains of mechanical behaviour: polycrystalline, multicrystalline and quasi-single crystalline depending on the thickness and on the number of grains across the thickness. The transition between the three domains is due to the occurrence of surface effects involving a decrease in the long-range internal backstress revealed by the TEM observations. [less ▲]

Miniaturization induced size effects: Experimental and numerical investigation of size effects linked to the miniaturization of metallic components

in Scale transition for plastic crystalline and microstructured materials: from experiment to numerical modeling (2010)

The manufacturing of small metallic components for MEMS is a great challenge for industries. However, the lack of knowledge about the mechanical behavior of metals when they are employed in small ... [more ▼]

The manufacturing of small metallic components for MEMS is a great challenge for industries. However, the lack of knowledge about the mechanical behavior of metals when they are employed in small components can reduce the economical development of MEMS due to manufacturing and reliability issues. The objective of this work is to provide new scientific results to improve the understanding of the mechanical properties of micro-components. Experimental and numerical (strain gradient plasticity model) tensile tests are performed on thin nickel single crystals and polycrystals (thickness larger than 10 m) showing different size effects depending on the dimensions of the samples. These effects are then taken into account in new simplified numerical models for the prediction of micro-forming processes. [less ▲]