| Summary: | 碩士 === 國立臺灣科技大學 === 機械工程系 === 101 === The research studies the nanometric cutting of Au50Ag50 alloy bulk with the diamond tool by molecular dynamics. Using different cooling rates as a parameter conditions to explore the curing material microstructure changes. And using the same cooling conditions with cutting simulation experiments to explore the degree of crystallinity after cutting and cutting force and the shear angle on the shear plane. The interactions between atoms in the workpiece are described by a embedded-atom method(EAM) and Tight-binding(TB) and Morse potential.
The simulation results shows that when the faster the cooling rate after solidification within the bulk lower crystallinity; contrary, the slower cooling rate after solidification within the bulk higher crystallinity. Increase the relaxation time at room temperature can not effectively improve the crystalline material, to obtain a high degree of crystallinity, the slower the cooling rate should be used, or the use of appropriate crystal seed. Cutting tool to give material systems due to mechanical work can induce crystallization, the machined surface to enhance the degree of crystallinity. With the increased degree of crystallinity of the material, the cutting force also went up with the reverse Hall-Petch effect consistent. Compared to the single crystal of silver (001) [1 ¯00] cutting direction, the component ratio of 1:1 gold / silver alloy bulk cutting force and will improve as the crystallinity increases. Because the single crystal material has a plurality of sliding systems, therefore, change the cutting angle of shear rate of more large crystalline material.
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