Year

2022

Degree Name

Doctor of Philosophy

Department

School of Mechanical, Materials, Mechatronic and Biomedical Engineering

Abstract

The major objective of this thesis was to explore an intelligent manufacturing method which is capable to fabricate high entropy alloys (HEAs) efficiently, and then to design new types of HEAs for use within a nuclear reactor environment. The microstructures, phase characterization and mechanical properties of alloys were investigated.

Powder arc additive manufacturing (PAAM) having a high level of controlling local forming procedure was established to fabricate HEAs in-situ. This new manufacturing process possesses time and cost saving, and rapid cooling rate which can reduce the segregation of material in comparison to traditional methods. AlCoCrFeNi2.1 eutectic HEA which simultaneously possesses high strength and high ductility was used as a prime example to verify the feasibility of PAAM system. Different times (1,3,6) remelting process which is typically applied in arc melting to improve the homogeneity of prepared material was compared in this research. The applied layer-remelting process shows negligible effects on the phase fractions and their compositions; however, it significantly degraded the tensile strength and ductility of prepared alloys. Particularly, the ductility of the alloy reduced dramatically from about 27% after one time layer-remelting to only about 3% after 3 times layer-remelting.

FoR codes (2008)

0910 MANUFACTURING ENGINEERING, 0912 MATERIALS ENGINEERING, 0913 MECHANICAL ENGINEERING, 0202 ATOMIC, MOLECULAR, NUCLEAR, PARTICLE AND PLASMA PHYSICS

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Unless otherwise indicated, the views expressed in this thesis are those of the author and do not necessarily represent the views of the University of Wollongong.