Browsing by Author "Chou, C. -P."

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Effect of nanomechanical and microstructural properties on annealed multilayer Si0.8Ge0.2-Si films
(2012-04-01)
Lin, T. -Y.
;
Tsai, C. -H.
;
Yau, W. -H.
;
Chou, C. -P.
;
機械工程學系
In this study, ultrahigh vacuum chemical vapour deposition was employed to deposit multilayered silicon-germanium (SiGe) films. Subsequently, we take those samples for ex situ thermal treatments in the furnace system (400 and 500 degrees C). The periodic multilayer SiGe with different annealing conditions measured by a commercial nanoindenter observed the slight increase in hardness. The cross-section profile and the microstructure of SiGe multilayer films were characterised by means of atomic force microscopy and transmission electron microscopy. The effect of the thermodynamics of the thin film/substrate system is evidenced by annealing treatment. It is demonstrated that the SiGe multilayer films are more susceptible to plastic deformation while annealing treatments are carried out. The misfit dislocations in the critical pile-up event were observed in the periodical SiGe multilayer that can be relaxed at thermal annealing, thus providing the nanomechanical performance.
Effects of stress relief coupled with reduced EBW energy on flow formed maraging steel weldment
(2008-07-01)
Lee, Y. -J.
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Wu, S. -C.
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Chang, J. -L.
;
Chou, C. -P.
;
Lee, I. -K.
A flow formed C-250 maraging steel tubing was welded by electron beam welded (EBW) process and subsequently age hardened. Conventional EB welding with high energy input had resulted in seriously inadequate percentage elongation of the weldment. With an additional prewelding stress relief treatment and EBW with a lower energy input, the elongation of the weldment showed significant improvement after being treated with age hardening. It was found that the tensile strength was increased by 12% and the percentage elongation was remarkably increased by 92%.