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Effect of Annealing on Hardness and Elastic Modulus of Invar36 Thin Films Deposited by Direct Current Sputtering for Strain Gauge Applications |
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PP: 119-129 |
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doi:10.18576/ijtfst/080304
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Author(s) |
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H. M. Kalpana,
V. Siddeswara Prasad,
T. N. Satish,
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Abstract |
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| Invar36 thin film was deposited at room temperature on p-type silicon (100) substrates using DC magnetron sputtering technique. In order to investigate the post-annealing effect on the structural characteristics and mechanical properties of the prepared films, they were vacuum annealed for one hour at different temperatures viz. 200°C, 400°C and 500°C. Composition analysis, phase structure, microstructure and roughness of as-deposited and annealed Invar36 thin films were investigated by energy dispersive X-ray analysis (EDX), X-Ray diffraction (XRD) and Atomic Force Microscopy (AFM). Mechanical properties of Invar36 thin films were studied by nano indentation method. EDX analysis revealed a variation in nickel content with annealing. The XRD measurements indicated the phase transformation of Invar36 thin film with annealing. AFM analysis implied uniform surface morphology of the films, increase of surface roughness and grain size with annealing. The hardness (H) of the film decreased with annealing. Hardness of as-deposited, annealed at 200oC, 400oC and 500oC were found as 8.5±0.96 GPa, 7.64±0.35 GPa, 6.34±0.14GPa and 3.95±1.05 GPa, respectively. The elastic modulus of Invar36 thin films was increased with annealing. Elastic modulus of as-deposited, annealed at 200oC, 400oC and 500oC were found as 157.00±25.49 GPa, 166.0±11.8 GPa, 172.00±9.93 GPa and 176.00 ±10.78 GPa, respectively. These results are explained on the basis of the change of microstructure after annealing and the effect of the same on the mechanical properties of Invar36 thin films for strain gauge applications. |
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