Influence of Processing Parameters on the Mechanical Properties of HPT-Deformed Nickel Carbon Nanotube Composites

TL;DR

This study explores how high-pressure torsion deformation parameters influence the microstructure and mechanical properties of nickel-carbon nanotube composites, highlighting temperature as a key factor for optimization.

Contribution

It demonstrates the effect of HPT deformation temperature on microstructure refinement and mechanical behavior, providing insights for optimizing composite performance.

Findings

Higher deformation temperatures increase Nickel grain size.

Carbon nanotube agglomerates become smaller and more evenly distributed.

Mechanical anisotropy decreases with higher deformation temperatures.

Abstract

Nickel carbon nanotube composites with varying amounts of carbon nanotubes are deformed by high pressure torsion at different deformation temperatures to high strains, where no further refinement of the Nickel matrix microstructure is observed. Mean Nickel grain sizes increase with increasing HPT deformation temperature, while the size of the carbon nanotube agglomerates is significantly reduced. Additionally, the distribution of the agglomerates in the metal matrix becomes more homogenous. To investigate the mechanical performance of the HPT deformed composites, uniaxial tensile and compression tests are conducted. Depending on the HPT deformation temperature and the resulting microstructure, either brittle or ductile fracture occurs. Increased HPT deformation temperatures induce a decrease in the anisotropy of the mechanical properties, mainly caused by a shrinking of the carbon nanotube agglomerates. It is shown, that tuning the HPT deformation temperature is the key for optimizing both the microstructure and the mechanical performance.