Effect of Boron on Electrical and Thermal Conductivities of Aluminum

Aluminum has been used as an alternative material for copper, due to its good electrical and thermal conductivities. However, small quantities of transition elements such as Ti and V affect the conductivities of aluminum. Therefore, in this study, the influence of B addition to reduce the effects of Ti and V on the conductivities of aluminum was investigated. Both the electrical and thermal conductivities of aluminum were improved with addition of B up to 0.05 wt%, while the conductivities were gradually reduced with an excess amount of B. SEM-EDS and XRD results exhibited that B reacted with Ti and V element to form diborides, such as TiB 2 and VB 2 phase, and those diborides tended to settle down to the bottom of the crucible because their densities were higher than that of aluminum melt. As a result, B reduced the deleterious effects of Ti and V, and the electrical and thermal conductivities of aluminum were improved.