Speaker
Description
The behavior of ceramics at the nanometer scale strongly differs from the one of the corresponding bulk material. For instance, strong plastic deformation has recently been reported in isolated nanometer-sized alumina nanoparticles or MgO nanocubes, when tested in situ in a transmission electron microscope (TEM). This plastic behavior may also occur in a powder during the compaction process, even at room temperature. An effect of nanoparticle surfaces may also have to be considered in the plastic behavior of nanoparticle during compression since it can affect the deformation mechanism or induce phase transformation. Controlling plastic deformation of nanoparticles during the ceramics processing might be a way to enhance their properties or to improve the processing route (compaction and sintering steps, for instance). We present here a comprehensive study of the mechanical behavior of transition alumina in the compacted powder.
Transition alumina nanoparticles, stored in different atmospheres to modify the nanoparticle surfaces, have been compacted at room temperature under 15 GPa in a Paris-Edimbourg press. XRD analysis have been performed on the compacted powder to monitor a possible phase transformation of alumina.
Thin foils of these compacted powders have been prepared by Focused Ion Beam machining (FIB) and analysed by TEM. In situ nanocompression tests have then been performed on the different thin foils to compare the behavior of the compacted powder depending on the nanoparticle surfaces of the initial powder. Several imaging conditions have been investigated to follow the nanoparticle movement and/or their deformation during the compression. The results obtained on the compression of thin foils will be presented and discussed in function of the sample microstructure.
| Speaker Country | France |
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