Abstract: An aluminum alloy is prepared from an aluminum alloy powder having a composition of:lubricating componentPb: 3 to 15 Wt %;hardening componentSi: 1 to 12 Wt %;rainforcement componentone or more selected among Cu, Cr, Mg, Mn, NiZn, Fe and: 0.2 to 5.0 Wt %;and remainder of aluminum as principal material or matrix.To the aluminum alloy powder set forth above, powder state Pb in 3 to 12 Wt % is added. With the mixture of the aluminium alloy powder and Pb powder, a billet is formed. For the billet, extrustion process is performed in a extrusion ratio greater than or equal to 40. In the extruded block, Si particle dispersed in the aluminum matrix is in a grain size smaller than or equal to 12 .mu.m. Furthermore, at least of half of added Pb power particle is dispersed to have greater than or equal to 0.74 of circularity coefficient.

Abstract: The invention provides an aluminum base bearing alloy which is excellent in both lubricating capability and fatigue resistance and is useful, e.g. in automotive engines. The bearing alloy consists essentially of at least one lubricating element such as Pb and/or Sn the total amount of which is more than 0.04 and not more than 0.07 by sectional area ratio to the aluminum matrix, Si the amount of which is in the range from 0.01 to 0.17 by sectional area ratio to the aluminum matrix, 0.2-5.0 wt % of at least one reinforcing element such as Cu and/or Cr, 0-3.0 wt % of at least one refining element such as Ti and/or B and the balance of Al. The grain size of the lubricating element(s) is not larger than 8 .mu.m, and the grain size of Si is not larger than 12 .mu.m and preferably not smaller than 6 .mu.m.