Evaluation of the Strength of Thin Metallic Films Coated on Brittle Materials by using an Indentation Fracture Method
Nanoindentation techniques are poplar methods which are used for the evaluation of the hardness and elastic modulus of very thin films. However, since the plastic and elastic regions formed underneath the indenter are much larger than its penetration depth, the thickness of films, which can be used for the nanoindentation measurement, is limited to a certain value. In the present study, microcracking caused by micro-Vickers indentation was applied to the evaluation of the tensile properties of very thin metallic films coated on brittle materials. For this purpose, gold films with the thicknesses ranging from 23 nm to 227 nm were coated on glass substrates, and the lengths of radial cracks before and after coating were measured. The crack opening displacements in uncoated glass were also measured to assess the stress intensity factor at crack tips. In the case of 34 nm thick gold film, a fracture mechanics analysis based upon the crack-tip stress intensity factor led to the yield strength of about 620 MPa and the fracture toughness of 2.0 MPa·m1/2. The evaluation of mechanical properties of thicker films, however, became more difficult, since the elongation in thicker films are considered to become comparable with the crack opening displacement.
Thin film Indentation fracture Mechanical properties Stress intensity factor crack opening displacement
Yuzo Nakamura Takashi Kawabata Shinya Ishigami Jun Wakiyama Yoshikazu Maeda
Department of Mechanical Engineering,Graduate School of Science and Engineering Department of Nanostructure Advanced Materials,Graduate School of Engineering,Kagoshima University,K Department of Nanostructure Advanced Materials,Graduate School of Engineering,Kagoshima University,K
国际会议
北京
英文
1-10
2013-06-16（万方平台首次上网日期，不代表论文的发表时间）