Speaker
Description
In view of global warming, the reduction of greenhouse emissions has become a central topic for the transportation sector. In this context, the development of light metals is attracting attention for structural applications. Nanoparticle reinforced metal composites are a promising solution due to potentially excellent mechanical properties and low density. However, experimental results fall short of the theoretical predictions. The reinforcing mechanisms acting in nanoparticle composites are also not yet well understood.
The well understood strengthening mechanisms for metal composites are load transfer, Orowan strengthening, grain refinement and thermal mismatch as summarised in our previous work [1]. However, those mechanisms were formulated for micrometre-sized particles and therefore have certain limitations when applied to nano-reinforcements.
Load transfer: requires good interfacial bonding between nanoparticle and metal matrix, which is said to be poor according to some research.
Orowan strengthening: It is not clear whether dislocation motion in the context of nanoparticles requires the formation of Orowan loops, or whether the strain caused by shearing of the metal around nanoparticles can be accommodated by deformation or failure of the nanoparticle-matrix interface leading to a quasi-cutting mechanism.
Grain refinement: There is no clear evidence of nanoparticles acting as nuclei due to their nano-scaled dimension.
Thermal mismatch: It is unclear to which extent the analysis of Arsenault [2] developed for micron sized particles can be applied to the scale and geometry of nanoparticles.
In this paper, we looked into using different nanoparticles including carbon nanotubes, graphene and SiC with different geometry in lightweight metal matrix. Both, experimental and theoretical results were compared to gain a better understanding on the influence of difference nanoparticles. We also discussed possible reinforcing mechanisms regarding nanoparticles based on both micro-scale observation and simulation.
[1] Q Li et.al Composites Science&Technology 2009; 69: 1993-1999.
[2]RJ Arsenault et.al Mater Sci&Eng 1986; 81: 175-87.
| Speaker Country | UK |
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