The effect of Si morphology on the microstructure and wear property of ZA48 alloy

To evaluate the influence of silicon morphology on the tensile property and wear behaviour of ZA48 alloy, the microstructure, tensile fracture and wear surface of Si–modified ZA48 alloy had been analysed with the aid of OM and scanning electron microscope (SEM). Metallographic studies showed that the phase Si was mainly existed in the matrix with fine bar shape eutectic Si phase and block primary phase Si. Under oil lubricant wear condition, the abrasion wear mechanism is seen at all test loads. SEM micrographs revealed that the hard Si particles were protruded from matrix, which forms a thin film at the contact surface between the composite and the counter face. It improved the wear resistance of the Zn–Al alloys. However, these coarse and block phase Si have a weak binding force with the base. It separates matrix seriously and weakens mechanical properties. The wear surface was also damaged by the larger particles owing to the weak binding force with the base.