Residual Stresses around Indentations in Alumina/SiC Nanocomposites
- PDF / 33,287 Bytes
- 1 Pages / 612 x 792 pts (letter) Page_size
- 81 Downloads / 149 Views
0977-FF04-28
Residual Stresses around Indentations in Alumina/SiC Nanocomposites Apichart Limpichaipanit and Richard Ian Todd Department of Materials, University of Oxford, Parks Road, Oxford, OX1 3PH, United Kingdom ABSTRACT Alumina/SiC nanocomposites are more wear resistance and have better surface finish than pure alumina of a similar grain size. Grain pullouts caused by intergranular fracture are observed on worn surface of alumina whereas only a few pullouts resulting from transgranular fracture and scratches caused by plastic deformation are the main features of a worn surface of the nanocomposites. Surface mechanical properties were investigated by Cr3+ fluorescence microscopy. The experiments were carried out using a variety of microstructures (i.e. nanocomposites with different amount of SiC and alumina of similar grain size). The result obtained from calculation of the centre of gravity of R1/R2 shows net compressive stress within and around indentation in both alumina and the nanocomposites as indicated by negative peak shifts compared to the polished and unstressed samples. Fig1 shows the nanocomposites with more SiC had more negative peak shift and hence more net compressive residual stress. The plastic deformation zone of alumina, which can be seen by brittle fracture when polishing the sample after indentation, was more extensive than the nanocomposites. That means alumina could be deformed more plastically within and around indentations and compressive stress resulting from indentation was less compared to the nanocomposites.
R1/R2 Centre of gravity
wavemunber (/cm)
14415 14410 alumina
14405
2 vol%
14400
5 vol%
14395
10 vol%
14390 14385 0
20
40
60
80
d (um)
Figure 1. Centre of gravity of R1/R2 from Cr3+ photoluminescence microscopy
Data Loading...
