Influence of TiB2 volume fraction on SiCp/AlSi10Mg composites by LPBF: Microstructure, mechanical, and physical properties

Abstract

Adding TiB2 particle to SiC particle reinforced Al composite to form TiB2-SiCp/Al composite can increase the tensile properties and lower the thermal expansion coefficient and friction coefficient of the material. The microstructures, mechanical properties, thermal expansion coefficient, and wear behavior of TiB2–SiC particles reinforced AlSi10Mg composites formed by laser powder bed fusion (L-PBF) were investigated in this study. The ultimate tensile strength, thermal expansion coefficient, and the friction coefficient of LPBF-formed 1 vol% TiB2-SiCp/AlSi10Mg composite are 477.6 MPa, 19.91 × 10−6 °C−1, and 0.38, respectively. The results show that the addition of 1 vol% TiB2 weakens the orientation of SiCp/AlSi10Mg composite in the (001) direction. The orientation tends to be random, and the coarse cellular grain with the best orientation in the (001) direction transforms into fine grains in the (111) and (101) directions gradually. This makes the microstructure of the composite be more refined and uniform, eradicating the anisotropy of the temperature gradient, and eliminating the internal stress concentration in the composite. The average grain size of the composite decreases from 3.68 to 1.52 μm. The primary strengthening mechanism of TiB2-SiCp/AlSi10Mg composites is dispersion strengthening. Theoretically, the ultimate tensile strength of the 1 vol% TiB2-SiCp/AlSi10Mg composite is expected to achieve 540.26 MPa.