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In this paper, TiCx particles were prepared by an in situ process and added to an Al-Bi alloy, and the effects of TiCx particles on the homogenization preparation and refinement mechanism of Al-Bi alloys were studied. The TiCx particle size can be greatly reduced by decreasing graphite particle size, and the TiCx particle size was further reduced after changing C source from graphite to MLG. The TiCx particle gradually changed from angular octahedral to truncated octahedral and then became round with the C/Ti ratio increasing from 0.4 to 1.0. After the TiCx particles being added to the Al-Bi alloy, it was found that TiCx had a significant inhibitory effect on the macrosegregation and coarsening of Bi phase. The average diameter of the Bi phase decreased from 4.32 μm to 3.45 μm with the TiCx particle size decreased, and the distribution became more dispersed and uniform, contributing to the heterogeneous nucleation and self-assembly behavior of TiCx particle. With the decreasing of TiCx particle size, the refinement mechanism evolved from heterogeneous nucleation to self-assembly. [ABSTRACT FROM AUTHOR]

The tribological properties of Pb‐free FeS/Cu–Bi (FCB) self‐lubricating composites were optimised with the Taguchi method. The effects of lubricant content and ball milling time on the anti‐friction and wear resistance of FCB composites were investigated. Then the evolution of the friction interface was observed through interrupted microscopy measurement to reveal its synergistic lubrication mechanism. The results showed that the primary and secondary factors that affected the anti‐friction and wear resistance of the FCB composites were FeS content, Bi content and ball milling time. The synergistic lubrication mechanism of FCB composites was that FeS could prevent the crack from extending with the continuous Bi mesh and could prevent the matrix with Bi debris from peeling off, which was conducive to the formation of a lubricant‐rich tribofilm at the friction interface to improve the tribological properties of the composites. [ABSTRACT FROM AUTHOR]

Nano Bi particles were subjected to chemical modification. The modified Bi particles were examined via field emission transmission electron microscopy, X-ray diffraction, infrared spectroscopy, and thermogravimetric analysis. Liquid paraffin oil (LPO) lubricants with different Bi/SiO2 contents were prepared through dispersion method by adding the modified nano Bi particles. The tribological properties of LPO containing Bi/SiO2 were determined using a tribometer. Results showed that the modified nano Bi particles were successfully coated with a layer of organic molecular chain, and the uniform dispersion and stability in lubricating oil were improved. Bi/SiO2 composite nanoparticles significantly improve the tribological properties of LPO, which benefits from the synergy among soft Bi, hard SiO2 particles, and LPO. [ABSTRACT FROM AUTHOR]