Strengthening effects of multi-walled carbon nanotubes reinforced nickel matrix nanocomposites

[摘要] The multi-walled carbon nanotubes (CNTs) reinforced nickel matrix nanocomposites (Ni-CNT) have been processed via ball milling followed by spark plasma sintering (SPS) process. The CNT content in these nanocomposites has been varied from 0.5 to 2 wt% (approximately from 2 to 8 vol%) to study their effect on the dispersion, microstructure, and mechanical behavior of these composites. Two Ni-CNT composite powders pre-mixing techniques have been employed, namely dry milling (DM) and solution ball milling (SBM), to investigate their effect on the dispersion of CNTs within a nickel matrix. The Ni-CNT powder was milled for different durations (1,2,6 and 12 hrs.) to investigate the milling effect on the grain size and the dispersion of CNTs in the nickel matrix. Ni-CNT nanocomposites exhibited improvement in microhardness and mechanical performance in comparison with pure nickel. Ni-1CNT-DM composites exhibited an excellent combination of the tensile yield strength of 455 MPa and around 13% elongation. This improvement in Ni-CNT nanocomposites is primarily attributed to the uniform dispersion of reinforcement within the nickel matrix, refined grain size, and strong nickel CNT interfacial bonding, which effectively transfers stress during tensile deformation. Various strengthening mechanisms associated with CNT-metal matrix composites have been discussed in detail. We have attempted to quantify the contribution of these strengthening mechanisms using micromechanical models. (c) 2021 Elsevier B.V. All rights reserved.

[发布日期] 2021-09-25

[关键词] Metal matrix composites (MMCs);Ball milling;Spark plasma sintering;Nickel matrix nanocomposites;Carbon nanotubes