Study of the Cu-Al Bimetal Interfacial Bonding and Its Effect on Electrical Conductivity

• Main Authors: Ting-Huang Jian, 簡廷皇
• Other Authors: Jhewn-Kuang Chen
• Format: Others
• Language: zh-TW
• Online Access: http://ndltd.ncl.edu.tw/handle/f8z5c2

碩士 === 國立臺北科技大學 === 材料科學與工程研究所 === 104 === The current study forms and observe the Cu-Al bimetallic interface to simulate the connections between aluminum end rings and Cu motor rotor. Heat treatments were applied to observe the evolution of Cu-Al interface structure while in service. The electrical conductivity was also measured to provide references for improved motor designs. This study uses two methods to form Cu-Al bimetallic interfaces: one by hot dipping Cu into Al at 680°C, and the other by hot pressing Cu and Al at 660°C. The interface structure consists of Cu9Al4, Cu3Al2, CuAl, CuAl2, and Al + CuAl2 eutectic layers. These intermetallics generally possess higher hardness than those of base metals. Among them, AlCu and Al3Cu4 exhibit much higher hardness, and thus lower fracture toughness, than that of CuAl2 and Cu9Al4. The 500°C heat treatment for 5 min helps to increase the uniformity of the interface layers. The coarser grains are formed to decrease the interface resistivity from 4.14×10-6 Ω in the as-hot-pressed interface to 2.32×10-6 Ω in the 500°C-5min heat treated interface. When the heat treatment time increases to over 60 min, the CuAl2 intermetallics grow exaggeratedly making the interface resistivity increasing from 2.32×10-6 Ω to 6.35×10-6 Ω.