The structural properties, elastic anisotropy, electronic structures and work function of D0₂₂-type Al₃TM (TM = Sc, Ti, V, Y, Zr, Nb, La, Hf, Ta) are studied using the first-principles calculations. The results indicate that the obtained formation enthalpy and cohesive energy of these compounds are in accordance with the other calculated values. It is found that the Al₃Zr is the most thermodynamic stable compound. The mechanical property indexes, such as elastic constants, bulk modulus, shear modulus, Young’s modulus, Poisson’s ratio, and Vickers hardness are systematically explored. Moreover, the calculated universal anisotropic index, percent anisotropy and shear anisotropic factors of D0₂₂-type Al₃TM are analyzed carefully. It demonstrates that the shear modulus anisotropy of Al₃La is the strongest, while that of Al₃Ta is the weakest. In particular, the density of states at Fermi level is not zero, suggesting that these phases have metal properties and electrical conductivity. More importantly, the mechanisms of correlation between hardness and Young’s modulus are further explained by the work function. Finally, the experimental design proves that D0₂₂-Al₃Ta has an excellent strengthening effect.

High lead–tin bronze is widely used in the selection of wear-resistant parts such as bearings, bearing bushes, aerospace pump rotors, turbines, and guide plates because of its excellent wear resistance, thermal conductivity, fatigue resistance, and strong load-bearing capacity. At present, high lead–tin bronze is used as a material for bimetal cylinders, which cannot meet the requirements of high-strength, anti-wear in actual working conditions under high temperature, high speed, and heavy load conditions, and is prone to de-cylinder, cylinder holding, copper sticking, etc. The reason for the failure of cylinder body parts is that the strength of copper alloy materials is insufficient, the proportion of lead in the structure is serious, and the wear resistance of the material is reduced. Therefore, it has important theoretical significance and application value to carry out research on the comprehensive properties of high-performance lead–tin bronze materials and reveal the strengthening and toughening mechanism. In this paper, The ZCuPb20Sn5 alloy is taken as the main research object, and the particle size, microstructure, mechanical properties, and friction of lead particles in ZCuPb20Sn5 alloy are systematically studied after single addition of B in ZCuPb20Sn5 alloy liquid. This paper takes ZCuPb20Sn5 alloy as the research object to study the effect of adding B on the morphology, microstructure, mechanical properties, and friction and wear properties of ZCuPb20Sn5 alloy lead particles, and discusses the strengthening and toughening mechanism of ZCuPb20Sn5 alloy under the action of B, and prepares a double high-performance lead–tin bronze alloy for metal cylinders. The main research results are as follows: The addition of B elements has an obvious refining effect on the α (Cu) equiaxed grains and lead particles in ZCuPb20Sn5 alloy. The average size of lead particles decreases from 30.0 µm to 24.8 µm as the B content increases from 0 wt.% to 0.1 wt.%. The reason for grain refinement is that B is easily concentrated at the grain boundary during the ZCuPb20Sn5 alloy solidification process, which affects the diffusion of solute atoms at the solidification interface, inhibits the grain growth, refines the grain, and hinders the sinking and homogenizes distribution between dendrites of lead; the tensile strength of the ZCuPb20Sn5 alloy improves. Relatively without B, when the addition of P is 0.1 wt.%, the tensile strength is the largest at 244.04 MPa, which enhances 13%; the maximum hardness gets 75.0 HB, which enhances 13.6%, as well as elongation get the maximum value at 17.2%. The main mechanism is that the addition of B forms a high melting point submicron Ni₄B₃ phase in the lead–tin bronze alloy. The Ni₄B₃ phase is dispersed in the matrix and strengthens the matrix. With the increase in B content (more than 0.1 wt.%), the Ni₄B₃ phase changes from sub-micron degree granular to micron degree block-like, and some defects such as shrinkage and porosity appear in the structure, resulting in a decrease in mechanical properties.

The effects of different Mn concentrations on the generalized stacking fault energies (GSFE) and elastic properties of Mn_xCoCrFeNi high-entropy alloys (HEAs) have been studied via first-principles, which are based on density functional theory. The relationship of different Mn concentrations with the chemical bond and surface activity of Mn_xCoCrFeNi HEAs are discussed from the perspectives of electronic structure and work function. The results show that the plastic deformation of Mn_xCoCrFeNi HEAs can be controlled via dislocation-mediated slip. But with the increase in Mn concentration, mechanical micro twinning can still be formed. The deformation resistance, shear resistance, and stiffness of Mn_xCoCrFeNi HEAs increase with the enhancement of Mn content. Accordingly, in the case of increased Mn concentration, the weakening of atomic bonds in Mn_xCoCrFeNi HEAs leads to the increase in alloy instability, which improves the possibility of dislocation.

The effects of Al–Ti–C and La on the fluidity of a ZL205A alloy after separate and combined addition were studied by conducting a fluidity test. The fluidity of the ZL205A alloy first increased and then decreased with the increasing addition of Al–Ti–C and La; it peaked at 0.3% and 0.1% for Al–Ti–C and La, respectively. The combined addition of Al–Ti–C and La led to better fluidity, which increased by 74% compared with the base alloy. The affecting mechanism was clarified through microstructure characterization and a DSC test. The heterogeneous nucleation aided by Al–Ti–C and La, the number of particles in the melt, and the evolution of the solidification range all played a role. Based on the evolution of the fluidity and grain size, the optimal levels of Al–Ti–C and La leading to both high fluidity and small grain size were identified.

To systematically investigate the diffusion behavior of Fe/Cu bimetallic materials and the influence of the Ni element on the diffusion and mechanical properties of the Fe/Cu bimetallic interface, the diffusion distance, diffusion coefficient, and strain–stress process based on molecular dynamics (MD) calculations and experimental testing were analyzed. All simulation results indicated that the liquid Cu matrix had a higher diffusion coefficient but hardly diffused into the Fe matrix, and the solid Fe matrix had a smaller diffusion coefficient but diffused deep into the Cu matrix at the same temperature. Compared with the initial state, the addition of nickel atoms to the Cu matrix favored the improvement of the diffusion coefficient and the diffusion distance of Fe/Cu bimetallic materials. Moreover, we found that the diffusion distance and the yield strength simultaneously increased and then decreased with the increase in Ni atoms, which is in agreement with the experimental test results. These improvements in the diffusion and mechanical properties were attributed to the enrichment of Ni atoms at the interface, but excessive Ni content resulted in deteriorated properties. Finally, our research described the enhancement mechanism of the addition of nickel atoms to the Fe/Cu bimetallic diffusion system. An analysis of the contributions of the diffusion distance, the diffusion coefficient, and the yield strength revealed that the diffusion properties of nickel atoms play an important role in Fe/Cu bimetallic materials.

The influence of the sub-nano Ni₃P and Cu₃P phases on the microstructure, mechanical properties, and strengthening mechanism of Cu–20Pb–5Sn-xP (x = 0,0.05,0.1,0.3,0.5) alloy were discussed under the addition of P to obtain a new Pb–Sn bronze alloy applying for bimetallic cylinder block. The results showed that the tensile strength and hardness of the Pb–Sn bronze alloy increase with the P contents, while the elongation increased first and then decreased. The main strengthen mechanism was that sub-nano Ni₃P and Cu₃P phases dispersed in the matrix, hindering the movement of dislocations during deformation. Additionally, the grain refinement also contributed to the improvement of mechanical properties. The Ni₃P phase is easier to form than the Cu₃P phase. And it is easier to combine with the matrix and more stable. The Ni₃P and Cu₃P phases were studied by using different characterization techniques, such as OM, SEM, EDS, XRD, TEM and First-principles, Phase diagram calculation method. When P is added to the alloy, the Ni₃P phase first appears in the alloy, and when the P content increases to more than 0.3 wt%, the Cu₃P phase begins to appear. This is because the Ni₃P phase is easier to form than the Cu₃P phase and is more stable. Only after part of P reacts with Ni dissolved in copper to form Ni₃P, the remaining P and Cu can form Cu₃P.