Understanding solidification and wear behaviour of Al-3Cu-Bi alloys

Abstract

Considering that Bi is able to decrease friction between contacting surfaces, wear damage is expected to decrease as well. Bi-containing Al alloys have emerged as a choice for creating self-lubricating parts. The current work compares the effects of two distinct Bi alloy contents on the microstructure, Bi morphology/spacing, hardness, and wear resistance of Al-3.0wt.%Cu-Bi alloys. The novelty is in determining the microstructure constituting the Al-Cu based alloys with different Bi additions. Also, functional relationships between the wear resistance and the Bi droplets are derived. Increasing the Bi content from 2.0 to 3.2 wt.% changed the size and spacing of Bi particles as well as decreased hardness and increased the wear resistance. Even though the Al-3.0wt%Cu-3.2wt%Bi alloy has a lower hardness, the greater Bi fraction seems to be the key factor enhancing wear resistance. The bigger Bi areas spreading over the Al-rich phase under wear allowed higher wear resistance.