Abstract
The deformation behavior of single crystal and nanocrystalline nickel were studied using in situ micropillar compression experiments from quasi-static to high strain rates up to 103 s−1. Deformation occurred by dislocation slip activity in single crystal nickel whereas extensive grain boundary sliding was observed in nanocrystalline nickel with a shift towards more inhomogeneous, localized deformation above 1 s−1. The strain rate sensitivity exponent was found to change at higher strain rates for both single crystal and nanocrystalline nickel, while the overall strain rate sensitivity was observed to be of the same value for both. With increasing high strain rate micropillar compression tests being reported, the issue of adiabatic heating in micropillars becomes important. We report crystal plasticity based finite element modeling to estimate the adiabatic heating, spatially resolved within the micropillar, at the highest tested strain rates. The simulations predicted a significant temperature rise of up to 200 K in nanocrystalline nickel at the grain boundaries, and 20 K in single crystalline nickel due to strain localization. Transmission Kikuchi Diffraction analysis of nanocrystalline nickel micropillar post compression at 103 s−1 did not show any grain growth.
| Original language | English |
|---|---|
| Article number | 102336 |
| Journal | Extreme Mechanics Letters |
| Volume | 77 |
| DOIs | |
| Publication status | Published - 14 Apr 2025 |
| MoE publication type | A1 Journal article-refereed |
Funding
N.G.M. and G.M. acknowledge financial support from Research Council of Finland (RCF grant no. 341050 ). This work made use of H2MIRI (funded through RCF grant number 353235 ) and Tampere Microscopy Center facilities at Tampere University .
Keywords
- Adiabatic heating
- Crystal plasticity
- High strain rate
- Micropillar compression
- Nickel
- Strain rate sensitivity