Tensile and high cycle fatigue tests of NiCo thin films

✍ Scribed by Jun-Hyub Park; Yun-Bae Chun; Yun-Jae Kim; Yong-Hak Huh; Dong-Joong Kang

• Publisher: Elsevier
• Year: 2011
• Tongue: English
• Weight: 376 KB
• Volume: 10
• Category: Article
• ISSN: 1877-7058
• DOI: 10.1016/j.proeng.2011.04.217

✦ Synopsis

This paper represents the results of tensile and fatigue tests of NiCo thin films, to investigate the effect of size on mechanical properties. The "dog-bone" type Specimen with reduced section widths of 50 m and 150 m were fabricated on two 6 inch wafers using electro-plating process and MEMS processes. The NiCo film thickness of one wafer was 7.23 m. The elastic moduli of the NiCo thin film specimens were about 183±4.1 GPa for the 50 m specimens and about 148±8.4 GPa for 150 m specimens. The ultimate tensile strengths for the 50 m and 150 m width specimens were 2431±87.8 and 2348±93.3 MPa, respectively. However, the difference between the tensile strengths of the specimens is low, at 3.3%. Fatigue tests were performed with 2 or 5 Hz in atmospheric air at room temperature under axial loading at a load ratio of R (=F min /F max ) = 0.1 in a load-control until complete failure. Fatigue strength coefficients of the specimens with 50 and 150 m width were 1785 and 1257 MPa, respectively. In addition, fatigue strength exponents of the specimens with 50 and 150 m width were 0.0818 and 0.0629, respectively.