Microstructure and morphology of Al–Pb bearing alloy synthesized by mechanical alloying and hot extrusion

The bearing alloy with the composition of Al–15%Pb–4%Si–1%Sn–1.5%Cu (mass fraction, %) was prepared by mechanical alloying and hot extrusion. By using X-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis, grain size, morphology and microstructure of mechanical alloyed powders and hot-extruded bulk alloy were investigated. The experimental results show that nano-crystalline phase and amorphous phase were achieved during MA. After milling for 40 h, the Al crystalline and Pb crystalline are 30 nm and 20 nm, respectively. In the bulk alloy hot extruded at 400 °C, the nanograin of Pb with about 65 nm remains, the submicro Al grain and some amorphous phase are observed, and the homogeneous microstructure and ultra-fine lead particles are obtained in aluminum matrix. σbe and σ0.2 of the bulk alloy hot extruded at 400 °C are up to 610 and 440 MPa, respectively, and hardness is exceeded 182HV5, which is higher than that of Al–Pb serial bearing alloys synthesized by other technology.