Microstructure and mechanical properties of TiC/AlSi10Mg alloy fabricated by laser additive manufacturing under high-frequency micro-vibration

TiC/AlSi10Mg alloys were successfully fabricated by laser additive manufacturing under high-frequency micro-vibration. The application of high-frequency micro-vibration during laser processing could accelerate the melt flow, promote the floating of gas and slag in the molten pool and significantly reduce the pores in the alloys, which could obtain refined and homogenous microstructure with superior alloy density as well as good performances with relatively high production efficiency. The effects of different vibrational frequencies on the microstructure and properties of the alloys have been systematically investigated. The microstructure, chemical composition, phase constituent, hardness distribution and tensile properties of the TiC/AlSi10Mg alloys were investigated by optical microscope (OM), scanning electron microscope (SEM), energy dispersive X-ray analysis (EDAX), X-ray diffractometer (XRD), Vickers micro-hardness tester, and high-precision electronic universal testing machine, respectively. The results shows that the structures of the TiC/AlSi10Mg alloys are refined by high-frequency micro-vibration. The size of the cellular grain is decreased from 4 to 13 mu m to 2-4 mu m. The overlap region of the molten pool could be divided into three parts: fine zone, coarse zone and heat affected zone (HAZ). The number of pores in the alloys is reduced by high-frequency micro-vibration and the density of the alloys is effectively improved. When the vibration frequency is 969 Hz, the structure is more compact and the defect in the alloy is the lowest, providing a good density (99.1%). In addition, the maximum average hardness is 183.3 HV0.05 at the vibration frequency of 969 Hz, and the maximum tensile strength and elongation are 314.7 MPa and 8.81% respectively at this vibration frequency, which are higher than those at other vibrational frequencies. (c) 2019 Elsevier B.V. All rights reserved.