Effect of Bond Types on Nanomechanical Properties and Deformation Behaviors of Single-crystalline Nanopillars

• Main Authors: Ting-Chun Lin, 林亭均
• Other Authors: Shou-Yi Chang
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/75443478320886314715

碩士 === 國立中興大學 === 材料科學與工程學系所 === 102 === Because of the high surface area/volume ratio and unique quantum effect, nanomaterials have different optical, electrical,magnetic, mechanical,chemical properties from bulk materials.Recent researches indicate that, at the nanoscale, the mechanical properties of materials are size-dependent. However,the effects of either size or bond type on mechanical properties or deformation behaviors have not been clarified. Therefore,the purpose of this study is to investigate the correlations between the size and mechanical properties and between the bond type and deformation behaviors of nanomaterials. The mechanical properties of one-dimensional nanorods were measured by using nanoindentation, and the size effect was discussed. The deformation behaviors of nanopillars with different bond types were further observed and analyzed by in-situ TEM/nanoindentation. Nanoindentation results (after contact area calibrations) showed a “size effect” in MgO nanorods, and the in-situ TEM/nanoindentations suggested a dislocation starvation/exhaustion phenomenon during the plastic deformation of nanopillars. The experimental results of nanopillars with different bond types indicated that Cu nanopillars had good ductility, MgO nanopillars were hard but brittle (like ceramics), while GaAs nanopillars of strong bonding showed a strong anisotropy. High-resolution TEM analyses verified that, in nanopillars with different bond types, dislocations glided along different directions (with specific angles to pillar longitude; 70o, 35o and 70o for Cu, MgO and GaAs respectively).