In this paper, an efficient design of a Ti-modified Al-Si-Mg-Sr casting alloy with simultaneously enhanced strength and ductility was achieved by integrating computational thermodynamics, machine learning, and key experiments within the Bayesian optimization framework. Firstly, a self-consistent Al-Si-Mg-Sr-Ti quinary thermodynamic database was established by the calculation of phase diagram method and verified by key experiments. Based on the established thermodynamic database, a high-throughput Scheil-Gulliver solidification simulation of the A356-0.005Sr alloy with different Ti contents was carried out to establish the “composition-microstructure” quantitative relationship of the alloy. Then, by combining the computational thermodynamic, machine learning, and experimental data within the Bayesian optimization framework, the relationship “composition/processing-microstructure-properties” of A356-0.005Sr with different Ti contents was constructed and validated by the key experiments. Furthermore, the optimum alloy composition of the Ti-modified A356-0.005Sr casting alloy was designed based on this integration method with the Bayesian optimization framework and verified by the experiments. It is anticipated that the present integration method may serve as a general one for the efficient design of casting alloys, especially in the high-dimensional composition space.

The phase equilibrium and phase transformation of the Al–Si–Y ternary system were investigated in 80 annealed alloys using an electron probe microanalysis (EPMA), X-ray diffractometry (XRD) and differential scanning calorimetry (DSC). The phase equilibrium at 773 K was determined, and the phase distribution and solid solubility of the Al–Si–Y isothermal section at 773 K were obtained. A total of 23 three-phase zones and 4 two-phase zones were obtained, and 2 new ternary compounds, AlSi₄Y₅ and Al₂Si₃Y₅, were identified from the non-aluminum-rich corner. Additionally, the phase transition temperatures of representative alloys were determined by the DSC method, and then the phase transition temperatures were processed to obtain the experimental points of vertical sections. In the Al–Si–Y alloy system, the phase diagrams of the vertical sections with X(Al) = 90 at.%, 80 at.%, 70 at.% and 60 at.% at the aluminum-rich corner were calculated, and then the experimental points were inserted into the vertical section phase diagrams. The results of the vertical sectional experiments obtained from the validation experiments are in good agreement with the vertical sectional data obtained from the calculations, indicating that the validated thermodynamic description is useful for the microstructure design of the aluminum-rich corner of the Al–Si–Y ternary alloy.

This work reports on the effect of the heavy rare earth element Er on Nd–Fe–B magnets by using a simple Er₆₉Fe₃₁ alloy additive, which is much less expensive than Dy and Tb elements. It was found that the corrosion resistance was improved with a minimal reduction in magnetic properties by rationally controlling the Er₆₉Fe₃₁ addition content. The main reason is that Er element partially replaces the Nd element at the edge of the main phase grain to form an (Er,Nd)₂Fe₁₄B shell with low H_A, which leads to a decrease in coercivity. However, the improvement in the corrosion resistance is mainly due to the Er₆₉Fe₃₁ alloy addition, which slows down the corrosion rate. Simultaneously, an investigation was conducted into the different advantages that target magnets when subjected to diverse heat treatment methodologies. The above findings may lead to the development of applications for other rare earth elements, thereby accelerating the development of low-cost permanent magnets comparable to commercially available sintered Nd-Fe-B magnets.

The isothermal section of the La–Co–Ni ternary system at 723 K has been constructed in this work by using X-ray diffraction (XRD), scanning electron microscopy, and energy dispersion spectroscopy techniques (SEM-EDS). The experimental results show no existence of ternary compounds at 723 K. The isothermal section consists of 16 two-phase regions and 8 three-phase regions. La₃Co and La₃Ni, La₂Co₃ and La₂Ni₃, La₂Co₇ and La₂Ni₇, and LaCo₅ and LaNi₅ form a continuous solid solution. The ternary solid solubility of Ni in LaCo₁₃ phase and La₂Co_1.7 phase was determined to be 15.61 at.% and 9.61 at.%, respectively. The solid solubility of Co in the LaNi₃, La₇Ni₃, and LaNi phases was 18.07 at.%, 5.62 at.%, and 8.49 at.%, respectively. The present experimental results are important for the design of La(Fe,Si)₁₃-based magnetic refrigeration materials.