Study on Superplastic Forming in Ce and Pd Based Bulk Metallic Glasses

• Main Authors: Hadi Wijaya, 黃祥進
• Other Authors: Jinn Chu
• Format: Others
• Language: en_US
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/61410777924172183309

碩士 === 國立臺灣海洋大學 === 材料工程研究所 === 94 === The purpose of this thesis is to study the superplastic forming of Ce70Al10Cu20 bulk metallic glass (BMG) as new rear earth based BMG with quite low glass transition temperature and the grating nanoforming of Pd40Ni40P20 BMG concerning its potential application. In previous study, the Pd-based BMG indicated the perfect Newtonian behavior at high temperatures and low strain rates. The compressive deformation behavior of a Ce70Al10Cu20 BMG in the supercooled liquid region was investigated at strain rates from 8x10-4 to 7x10-2 sec-1. The material exhibits excellent mechanical formability with a high compressive strain of ~89% at 8x10-4 sec-1 and 420 K. The material could be compressed from a thickness of 1 mm to ~106 μm. Excellent formability in the microscale was demonstrated when the sample was deformed in the supercooled liquid region. The result indicates this alloy is a promising material for fabricating microdevice. The nanoforming of Pd-based BMG on Si grating die and PMMA on Pd-based BMG grating die were examined at 650 K and 453 K, respectively. The forming pressure was 10 MPa for 600 s. Apparent colors of blue, green and red were identified from the Si grating die, Pd-based BMG and PMMA imprinted gratings as various incident angles affected the wavelength of reflective diffraction. The phase shifts in diffraction pattern are significant in PMMA than Pd-based BMG grating, since PMMA exhibited large shrinkage after forming. The diffraction efficiency values in Si and BMG gratings are compatible. Pd-based BMG could be the Si die replacing material for micro and nano replication. In addition, Pd-based BMG itself is an ideal material in nano device.