Generation of ultrafine grained Ni-CNT composites by severe plastic deformation

• Applicant: Dr.-Ing. Sebastian Suarez Vallejo
• Subject Area: Synthesis and Properties of Functional Materials
• Term: from 2015 to 2019
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 278621969

• Final Report Year: 2020

Final Report Abstract

This project explored the possibility of applying severe plastic deformation (specifically, high pressure torsion) as an innovative microstructural tailoring process to CNT-reinforced metal matrix composites (MMC). The influence of this highly-energetic top-down process on both, the microstructure of the matrix and the reinforcement, was analysed and explained with the aid of advanced characterization techniques. The work covers different aspects of these systems, ranging from the evolution of the microstructure of the metal, the reinforcement redistribution and homogenization, the defect state of both, the CNT and the metallic matrix and the composite stabilization against thermal inputs. Finally, the performance of the deformed composites was evaluated and the chemical and microstructural processes involved in the surface degradation by tribological loads was clarified. From the gained understanding of the SPD processing of CNT-MMC, we were able to show that it is indeed viable to use HPT to tailor their microstructure and, by using CNT as reinforcements, it is certainly possible to address one of the major weaknesses of nanocrystalline and ultrafine grained microstructures, namely: their thermal stability. We also showed that the application of this deformation method is not unlimited, since there are restrictions to the amount of accumulated strain that the reinforcement can withstand without significant damage. Furthermore, when considering the mechanical and tribological behaviour of the deformed composites, both cases present certain particularities as to how strong is the influence of the refined microstructure and the obtained metal/CNT interfaces on the tensile strength (for the former) and the friction and wear response (for the latter). Summarizing, we were able to successfully address the open questions resulting from the state of the art at the beginning of this research. We achieved this by optimizing the HPT process to obtain a stable and homogeneous CNT distribution, understanding its influence on the defect development on the CNT. Furthermore, we could understand and describe the interaction of the CNT with lattice defects induced by HPT on the matrix and correlate it to the thermal stability of the microstructure.

Publications

• Carbon Nanotube (CNT) -Reinforced Metal Matrix Bulk Composites: Manufacturing and Evaluation, in: M. Aliofkhazraei (Ed.), Diam. Carbon Compos. Nanocomposites, 1st ed., InTech, 2016: p. 180
  S. Suárez, L. Reinert, F. Mücklich
  
• Evolution of the microstructure in carbon nanotube reinforced Nickel matrix composites processed by high-pressure torsion, IOP Conf. Ser. Mater. Sci. Eng. 258 (2017), p. 012008
  K. Aristizabal, S. Suárez, A. Katzensteiner, A. Bachmaier, F. Mücklich
  
• Study of the structural defects on carbon nanotubes in metal matrix composites processed by severe plastic deformation, Carbon 125 (2017), pp. 156-161
  K. Aristizabal, A. Katzensteiner, A. Bachmaier, F. Mücklich, S. Suarez
  
• Temperature dependent structural evolution in nickel/carbon nanotube composites processed by high-pressure torsion, IOP Conf. Ser. Mater. Sci. Eng., 2017
  A. Katzensteiner, K. Aristizabal, S. Suarez, R. Pippan, A. Bachmaier
  
• On the reinforcement homogenization in CNT/metal matrix composites during severe plastic deformation, Mater. Charact. 136 (2018), pp. 375-381
  K. Aristizabal, A. Katzensteiner, A. Bachmaier, F. Mücklich, S. Suárez
  
• Evolution of the lattice defects and crystalline domain size in carbon nanotube metal matrix composites processed by severe plastic deformation, Mater. Charact. 154 (2019), pp. 344-352
  K. Aristizabal, A. Katzensteiner, M. Leoni, F. Mücklich, S. Suárez
  
• Friction and Tribo-Chemical Behavior of SPD-Processed CNT-Reinforced Composites, Lubricants 7 (2019), p. 75
  K. Aristizabal, A. Tayrac, A. Katzensteiner, A. Bachmaier, S. Suarez
  
• Influence of Processing Parameters on the Mechanical Properties of HPT-Deformed Nickel/Carbon Nanotube Composites, Adv. Eng. Mater. 21 (2019) p. 1800422
  A. Katzensteiner, T. Müller, K. Kormout, K. Aristizabal, S. Suarez, R. Pippan, A. Bachmaier
  
• Microstructural evolution during heating of CNT/Metal Matrix Composites processed by Severe Plastic Deformation, Scientific Reports 10 (2020), 857
  K. Aristizabal, A. Katzensteiner, A. Bachmaier, F. Mücklich, S. Suarez