|
Vol.44, No.10, 678 ~ 684, 2006
|
| Title |
| Strength Assessment of Thin Films Based on the Measurement of Nanoindentation-induced Plastic Deformation Zone |
| 이윤희 Yun Hee Lee , 김주영 Ju Young Kim , 허용학 Yong Hak Huh , 남승훈 Seung Hoon Nahm , 권동일 Dong Il Kwon |
|
|
|
| Abstract |
| Surface yield strength can be estimated by considering the force equilibrium around an indentation-induced plastic zone; the plastic zone dimension is a key information for this analysis. However, conventional approach has analogized the plastic zone radius from few cross-sectional line profiles of the remnant indent and yielded erroneous strength result. Thus, we tried to extract a two-dimensional closed boundary of the plastic zone in this study by plotting a contour graph for the surface pile-up. This image processing was applied to the strength characterization of 1.0 ~μm-thick Au film on Si substrate. However, shallow indentation for film-only deformation brought about weak surface pile-up, thereby producing the strength overestimation compared to the microtensile results. In order to explain this discrepancy we introduced the concept of impression volume conservation and redetermined an extent of the hemispherical elastic/plastic boundary. Based on the modified data, the recalculated yield strength at 1.0 mN was 255.5 ± 37.2 MPa, comparable with the microtensile strength 243 MPa. This testing result confirms validity of the modified characterization method for the indentation-induced plastic zone. |
|
|
| Key Words |
| nanoindentation, yield strength, pile-up contouring, impression volume conservation, matlab(R) visualization tool |
|
|
 |
|
