On the reinforcement homogenization in CNT/metal matrix composites during severe plastic deformation

TL;DR

This study investigates how carbon nanotubes distribute within nickel matrix composites during high pressure torsion, revealing mechanisms of agglomerate debonding and proposing a model to predict homogeneous phase distribution.

Contribution

It introduces a model predicting the minimum strain for uniform phase distribution in CNT/metal composites during HPT, validated by experimental data.

Findings

CNT agglomerates debond and become spherical at higher strains

The proposed model accurately predicts the minimum strain for homogeneous distribution

Experimental observations align with the model's predictions

Abstract

Carbon nanotube (CNT)-reinforced nickel matrix composites with different concentrations were processed by high pressure torsion (HPT). We thoroughly characterized the CNT agglomerates' spatial arrangement at different stages of deformation in order to extract information valuable for the optimization of the processing parameters and to elucidate the mechanisms involved during the processing of particle reinforced metal matrix composites by HPT. From the electron micrographs taken on the radial direction with increasing equivalent strains, we observed that CNT agglomerates debond by relative sliding between CNT during HPT, becoming spherical at higher stages of deformation. Furthermore, we introduced a model for the prediction of the minimum strain required for a homogeneous distribution of a second phase during HPT, which can be correlated to the material's three-dimensional structure and agrees well with the experimental data.