Microstructure and wear characteristics of rapidly solidified Al-Pb-Cu alloys

The microstructure and wear properties of rapidly solidified Al-XPb (X = 10 , 16 and 20 wt.%) and Al-16Pb-Y (Y = 4Cu or 4Cu-1Mg) alloy powders were inv estigated. In order to overcome the constraint of the miscibility gap betwe en Al and Pb under equilibrium conditions, both in the solid and the liquid states, the alloys were rapidly solidified to produce them in a segregatio n-free condition. Although the Pb particles showed relatively fine dispersi on in the Al matrix in all the alloys by this process, the Al-16Pb alloy wa s found to have the most favorable microstructure with discrete Pb particle s of about 0.5 mu m size. With the addition of Cu and Cu-Mg to Al-16Pb, cel lular structures were newly formed, not seen in the binary AI-Pb alloys. We ar properties of the Al-Pb binary alloys measured as a function of the slid ing speed, sliding distance, and applied load showed that the Al-16Pb alloy has the best wear resistance, as expected from the fine microstructural fe atures in this alloy. The wear resistance of the alloys containing Cu- and Cu-Mg was higher than that of the Al-16Pb alloy, due to the matrix strength ening by precipitation hardening. The wear mechanism was identified by exam ining the wear traces and wear debris. (C) 2000 Elsevier Science S.A. All r ights reserved.