Limits...
The rate sensitivity and plastic deformation of nanocrystalline tantalum films at nanoscale.

Cao Z, She Q, Huang Y, Meng X - Nanoscale Res Lett (2011)

Bottom Line: Nanoindentation creep and loading rate change tests were employed to examine the rate sensitivity (m) and hardness of nanocrystalline tetragonal Ta films.Experimental results suggested that the m increased with the decrease of feature scale, such as grain size and indent depth.The magnitude of m is much less than the corresponding grain boundary (GB) sliding deformation with m of 0.5.

View Article: PubMed Central - HTML - PubMed

Affiliation: National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, People's Republic of China. mengxk@nju.edu.cn.

ABSTRACT
Nanoindentation creep and loading rate change tests were employed to examine the rate sensitivity (m) and hardness of nanocrystalline tetragonal Ta films. Experimental results suggested that the m increased with the decrease of feature scale, such as grain size and indent depth. The magnitude of m is much less than the corresponding grain boundary (GB) sliding deformation with m of 0.5. Hardness softening behavior was observed for smaller grain size, which supports the GB sliding mechanism. The rate-controlling deformation was interpreted by the GB-mediated processes involving atomic diffusion and the generation of dislocation at GB.

No MeSH data available.


Related in: MedlinePlus

The mc versus indent depth for Ta films with d values of 10 and 20 nm. The inset presents the relation between ln(σ) and ln() at the peak load of 500 μN.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3211239&req=5

Figure 4: The mc versus indent depth for Ta films with d values of 10 and 20 nm. The inset presents the relation between ln(σ) and ln() at the peak load of 500 μN.

Mentions: In addition to ml, the creep strain rate sensitivity (mc) was also determined from indentation creep testing. The relation of ln (σ) versus ln() at peak load of 500 μN is plotted in the inset of Figure 4, where σ is indentation stress. The mc can be determined by obtaining the slope of the curves. The corresponding procedure is mentioned in our previous study [15]. The mc of Ta films at different values of h is shown in Figure 4. The mc increases with the decreasing h at nanoscale, especially at h less than about 80 nm, which exhibits an indentation size effect. The diffusion along tip/sample interface process is believed to be responsible for h-dependent mc. The diffusion path along the tip/sample interface depends on h, and it becomes weaker with the increasing h. This is consistent with the variation of the indent depth-dependent rate sensitivity. Moreover, the magnitude of mc when d = 10 nm of Ta film is much higher than that when d = 20 nm.


The rate sensitivity and plastic deformation of nanocrystalline tantalum films at nanoscale.

Cao Z, She Q, Huang Y, Meng X - Nanoscale Res Lett (2011)

The mc versus indent depth for Ta films with d values of 10 and 20 nm. The inset presents the relation between ln(σ) and ln() at the peak load of 500 μN.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211239&req=5

Figure 4: The mc versus indent depth for Ta films with d values of 10 and 20 nm. The inset presents the relation between ln(σ) and ln() at the peak load of 500 μN.
Mentions: In addition to ml, the creep strain rate sensitivity (mc) was also determined from indentation creep testing. The relation of ln (σ) versus ln() at peak load of 500 μN is plotted in the inset of Figure 4, where σ is indentation stress. The mc can be determined by obtaining the slope of the curves. The corresponding procedure is mentioned in our previous study [15]. The mc of Ta films at different values of h is shown in Figure 4. The mc increases with the decreasing h at nanoscale, especially at h less than about 80 nm, which exhibits an indentation size effect. The diffusion along tip/sample interface process is believed to be responsible for h-dependent mc. The diffusion path along the tip/sample interface depends on h, and it becomes weaker with the increasing h. This is consistent with the variation of the indent depth-dependent rate sensitivity. Moreover, the magnitude of mc when d = 10 nm of Ta film is much higher than that when d = 20 nm.

Bottom Line: Nanoindentation creep and loading rate change tests were employed to examine the rate sensitivity (m) and hardness of nanocrystalline tetragonal Ta films.Experimental results suggested that the m increased with the decrease of feature scale, such as grain size and indent depth.The magnitude of m is much less than the corresponding grain boundary (GB) sliding deformation with m of 0.5.

View Article: PubMed Central - HTML - PubMed

Affiliation: National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, People's Republic of China. mengxk@nju.edu.cn.

ABSTRACT
Nanoindentation creep and loading rate change tests were employed to examine the rate sensitivity (m) and hardness of nanocrystalline tetragonal Ta films. Experimental results suggested that the m increased with the decrease of feature scale, such as grain size and indent depth. The magnitude of m is much less than the corresponding grain boundary (GB) sliding deformation with m of 0.5. Hardness softening behavior was observed for smaller grain size, which supports the GB sliding mechanism. The rate-controlling deformation was interpreted by the GB-mediated processes involving atomic diffusion and the generation of dislocation at GB.

No MeSH data available.


Related in: MedlinePlus