Effect of high-frequency micro-vibration on microstructure and properties of laser cladding aluminum coatings

Successful fabrication of AlSiTiNi coatings has been achieved by laser cladding assisted by high-frequency micro-vibration. Under the high-frequency micro-vibration, the dendrites in the coating are fractured and fine structure is formed. A typical bimodal structure is found in the coatings. The bimodal structure could improve the comprehensive properties of the coatings. The partially melted particles are found to be embedded in the fully melted structure at the vibration frequency of 551 Hz. The XRD and EDS investigations show that the coatings mainly consist of FeAl and FeNi phase. The composition distribution of the coatings is uniform due to the intensified convection in the molten pool during laser cladding. The micro-hardness of the coatings shows that the highest hardness of the coating reaches 781 HV_0.2 and the average hardness is 725.2 HV_0.2 when the vibration frequency is 551 Hz. The friction coefficient of the coating increases slightly and the running-in period decreases. In addition, the friction coefficient is stable and the stable wear time is also prolonged. Moreover, the main wear form of the coating is abrasive wear with slight adhesive wear. The tearing layer of the grinding defect and the wear loss of the coatings fabricated under the high-frequency micro-vibration are both decreased.