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Unique mechanical properties of nanostructured transparent MgAl2O4 ceramics.

Zhang J, Lu T, Chang X, Wei N, Qi J - Nanoscale Res Lett (2013)

Bottom Line: These tests were carried out on samples at different applied loads ranging from 300 to 9,000 μN.The elastic recovery for nanostructured transparent MgAl2O4 ceramics at different applied loads was derived from the force-depth data.Finally, the experimentally measured hardness and Young's modulus, as derived from the load-displacement data, are as high as 31.7 and 314 GPa, respectively.

View Article: PubMed Central - HTML - PubMed

Affiliation: School of Physics and Optoelectronic Engineering, Ludong University, Yantai 264025, People's Republic of China. zhjie126@126.com.

ABSTRACT
Nanoindentation tests were performed on nanostructured transparent magnesium aluminate (MgAl2O4) ceramics to determine their mechanical properties. These tests were carried out on samples at different applied loads ranging from 300 to 9,000 μN. The elastic recovery for nanostructured transparent MgAl2O4 ceramics at different applied loads was derived from the force-depth data. The results reveal a remarkable enhancement in plastic deformation as the applied load increases from 300 to 9,000 μN. After the nanoindetation tests, scanning probe microscope images show no cracking in nanostructured transparent MgAl2O4 ceramics, which confirms the absence of any cracks and fractures around the indentation. Interestingly, the flow of the material along the edges of indent impressions is clearly presented, which is attributed to the dislocation introduced. High-resolution transmission electron microscopy observation indicates the presence of dislocations along the grain boundary, suggesting that the generation and interaction of dislocations play an important role in the plastic deformation of nanostructured transparent ceramics. Finally, the experimentally measured hardness and Young's modulus, as derived from the load-displacement data, are as high as 31.7 and 314 GPa, respectively.

No MeSH data available.


Related in: MedlinePlus

SPM image and corresponding cross-sectional profile. SPM image of an indented area (A) and the corresponding cross-sectional profile (B) along the bluish grey line in (A).
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Figure 2: SPM image and corresponding cross-sectional profile. SPM image of an indented area (A) and the corresponding cross-sectional profile (B) along the bluish grey line in (A).

Mentions: Images of the nanoindentation were captured by the SPM mode, as shown in Figure 2A, which confirms the absence of any cracks and fractures around the indented zone. Instead, the flow of the material along the edges of indent impressions can be clearly seen. This flow is substantiated via a line trace of SPM images along the diagonal section of the selected indent (bluish grey line in Figure 2A). The corresponding cross-sectional profiles are displayed in Figure 2B. Similar pile-ups around the indentation were observed in the nanocrystallization during the nanoindentation of a bulk amorphous metal alloy at room temperature, indicating the severity of plastic flow around this region during indentation [18]. Moreover, polycrystalline hydroxyapatite is reported to exhibit plasticity at higher temperature [19,20], but no plasticity has been reported at room temperature for nanostructured transparent ceramics. Furthermore, for ceramic materials, the plasticity is limited at low loads, and the influence of dislocation can be important [21,22]. Thus, the faceted pile-up region suggests that dislocations generated during the indentation are attributed to the residual strain of nanostructured transparent ceramics.


Unique mechanical properties of nanostructured transparent MgAl2O4 ceramics.

Zhang J, Lu T, Chang X, Wei N, Qi J - Nanoscale Res Lett (2013)

SPM image and corresponding cross-sectional profile. SPM image of an indented area (A) and the corresponding cross-sectional profile (B) along the bluish grey line in (A).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3672023&req=5

Figure 2: SPM image and corresponding cross-sectional profile. SPM image of an indented area (A) and the corresponding cross-sectional profile (B) along the bluish grey line in (A).
Mentions: Images of the nanoindentation were captured by the SPM mode, as shown in Figure 2A, which confirms the absence of any cracks and fractures around the indented zone. Instead, the flow of the material along the edges of indent impressions can be clearly seen. This flow is substantiated via a line trace of SPM images along the diagonal section of the selected indent (bluish grey line in Figure 2A). The corresponding cross-sectional profiles are displayed in Figure 2B. Similar pile-ups around the indentation were observed in the nanocrystallization during the nanoindentation of a bulk amorphous metal alloy at room temperature, indicating the severity of plastic flow around this region during indentation [18]. Moreover, polycrystalline hydroxyapatite is reported to exhibit plasticity at higher temperature [19,20], but no plasticity has been reported at room temperature for nanostructured transparent ceramics. Furthermore, for ceramic materials, the plasticity is limited at low loads, and the influence of dislocation can be important [21,22]. Thus, the faceted pile-up region suggests that dislocations generated during the indentation are attributed to the residual strain of nanostructured transparent ceramics.

Bottom Line: These tests were carried out on samples at different applied loads ranging from 300 to 9,000 μN.The elastic recovery for nanostructured transparent MgAl2O4 ceramics at different applied loads was derived from the force-depth data.Finally, the experimentally measured hardness and Young's modulus, as derived from the load-displacement data, are as high as 31.7 and 314 GPa, respectively.

View Article: PubMed Central - HTML - PubMed

Affiliation: School of Physics and Optoelectronic Engineering, Ludong University, Yantai 264025, People's Republic of China. zhjie126@126.com.

ABSTRACT
Nanoindentation tests were performed on nanostructured transparent magnesium aluminate (MgAl2O4) ceramics to determine their mechanical properties. These tests were carried out on samples at different applied loads ranging from 300 to 9,000 μN. The elastic recovery for nanostructured transparent MgAl2O4 ceramics at different applied loads was derived from the force-depth data. The results reveal a remarkable enhancement in plastic deformation as the applied load increases from 300 to 9,000 μN. After the nanoindetation tests, scanning probe microscope images show no cracking in nanostructured transparent MgAl2O4 ceramics, which confirms the absence of any cracks and fractures around the indentation. Interestingly, the flow of the material along the edges of indent impressions is clearly presented, which is attributed to the dislocation introduced. High-resolution transmission electron microscopy observation indicates the presence of dislocations along the grain boundary, suggesting that the generation and interaction of dislocations play an important role in the plastic deformation of nanostructured transparent ceramics. Finally, the experimentally measured hardness and Young's modulus, as derived from the load-displacement data, are as high as 31.7 and 314 GPa, respectively.

No MeSH data available.


Related in: MedlinePlus