An Al-Cu alloy ingot was produced with the application of ultrasonic melt treatment. The effects of ultrasonication on the grain structure, eutectic phase, solution, and tensile properties of the alloy were analyzed. The volume and distribution of the eutectic phase were quantitatively evaluated based on stereological theory. The results are as follows: The grain-refinement efficiency at the center, 1/2 radius and edge of the ingot is 33.99%, 45.2% and 41.68%, respectively, under the action of an ultrasonic field. Ultrasonics improves the solid solubility of the Al-Cu alloy element, in which the solid solubility of Cu increases from 0.85% to 1.42%. The ultrasonic field improves the dispersion degree of the eutectic phase and reduces the volume fraction and eutectic phase number per unit volume. The mechanical properties of the Al-Cu alloy were improved by an ultrasonic field.

In this work, we fabricated VCp-reinforced iron-based composites (VCFCs) by adjusting the amount of Mn elements and investigated how the concentration of Mn affected the microstructural characteristics of Vanadium carbide (VC) and the texture of the iron matrix, and the influence of microstructure on tribological behaviors should be investigated. We demonstrated that VC changed from thick dendrite crystals (~50 μm) to tiny equiaxed crystals (~5 μm). Furthermore, the nucleation mechanism of VC also transformed from homogeneous nucleation to heterogeneous nucleation due to the lower Gibbs free energy of TiC and the tailoring effect of the Mn elements. In addition, γ-Fe in the FCC structure gradually increased and ascribed an increase of Mn content to the lower transformation temperature of martensite. Furtherly, particulate features and phase constitution could contribute to hardness and wear resistance. Higher hardness and excellent wear resistance occurred in the 3.0 Mn sample, which had a hardness of 869 HV and a wear rate of 1.77 × 10−6 mm3/(N·m). In addition, the adhesive wear could be the main wear mechanism in the 3.0 Mn sample, while the abrasive wear could be in the 4.5 Mn sample.