High Strain Rate Compressive Deformation Behavior of Nickel Microparticles

TL;DR

This study investigates the rate- and temperature-dependent mechanical behavior of nickel microparticles, combining experiments and molecular dynamics simulations to understand deformation mechanisms at extreme conditions relevant for miniaturized technologies.

Contribution

It provides the first comprehensive analysis of nickel microparticles' mechanical response over wide strain rate and temperature ranges, bridging experimental and simulation data.

Findings

Rate-dependent deformation behavior identified

Dislocation nucleation mechanisms analyzed

Size and temperature effects characterized

Abstract

Understanding the mechanical properties of metals at extreme conditions is essential for the advancement of miniaturized technologies. As dimensions decrease, materials will experience higher strain rates at the same applied velocities. Moreover, the interplay effects of strain rates and temperatures are often overlooked and could have critical effects in applications. In this study, for the first time, the rate-dependent and temperature-dependent mechanical response of nickel microparticles have been investigated. The microparticles were obtained by solid-state dewetting of nickel thin films deposited on c-sapphire. They exhibit self-similar shapes with identical sets of planes, facilitating straightforward comparison between particles. This research represents the first in-depth analysis of the mechanical properties of nickel single crystal dewetted microparticles across six orders of magnitude at room temperature and three orders of magnitude at 128 K. Molecular dynamic simulations (MD) were conducted in parallel on particles with the same faceting. In this work, the gap between experiments and simulations has been reduced to over one order of magnitude in size and 3 orders of magnitude in the strain rates. The thermal activation parameter analysis and MD simulations were employed to ascertain whether homogeneous or heterogeneous dislocation nucleation was the dominant mechanism controlling deformation in the particles.