Magnesium (Mg) alloys are the lightest structural metallic materials in engineering use, and their adoption in transport, electronics, and biomedical applications continues to be limited by casting-related defects and limited room-temperature ductility associated with conventional liquid-metal casting routes such as high-pressure die casting. Rheocasting, in which a partially solidified slurry containing fine, non-dendritic (globular or rosette) primary α -Mg particles is shaped directly from the semi-solid state, has emerged as one of the most industrially promising strategies for overcoming these limitations. This review synthesises the current understanding of rheocasting of Mg-based alloys across three themes: (i) the physical metallurgy of non-dendritic slurry formation and the principal slurry-generation technologies, including mechanical and electromagnetic stirring, cooling-slope and gas-bubbling routes, enthalpy-exchange/new-rheocasting processes, and solid-state strain-induced melt activation; (ii) the microstructural features that develop in rheocast Mg-Al-Zn (AZ), Mg-Al-Mn (AM), Mg-Sn, and Mg-rare-earth (Mg-RE) alloy systems, together with their evolution during subsequent solution and ageing heat treatment; and (iii) the resulting tensile, hardness, and defect-sensitive mechanical properties, benchmarked against conventionally cast and thixocast counterparts. A representative process schematic, a classification of slurry-preparation routes, and tabulated mechanical-property data compiled from the literature are presented. The review concludes by identifying persistent challenges including cost-effective slurry-quality control, scale-up for thin-wall die casting, and the extension of rheocasting to higher-performance Mg-RE alloys, as the principal directions for future research.
The increasing demand for lightweight, integrated, and low-carbon high-end equipment has placed more stringent requirements on the casting quality, functional integration, and service reliability of aluminum alloy housings. With its advantages in near-net-shape manufacturing, part integration, and high-volume production, integrated die casting has emerged as an important manufacturing route for electric-drive system housings in new energy vehicles, motor housings in high-end construction machinery, and housings for large electric-drive equipment. This review systematically examines recent advances in integrated die casting of aluminum alloy housings for high-end equipment, focusing on alloy systems, forming processes and process control, microstructural evolution and defect control, mechanical and functional performance evaluation, and engineering applications. The literature indicates that Al-Si and Al-Mg die-casting alloys constitute the principal material systems, while heat-treatment-free, high-strength and high-ductility, high-thermal-conductivity, and recycled aluminum alloys represent major directions in alloy development. High-pressure and high-vacuum die casting, optimization of gating, venting, and overflow systems, die thermal management, and digital process control play critical roles in improving the casting quality and production consistency of large, complex housings. Variations in wall thickness, melt flow paths, shot-sleeve thermal history, and local cooling conditions contribute to microstructural heterogeneity, second-phase segregation, the accumulation of externally solidified crystals, and nonuniform porosity distributions, thereby affecting mechanical properties, fatigue behavior, thermal conductivity, and sealing reliability. Future research should further strengthen the links among alloy design, process control, microstructural and defect characterization, performance evaluation, and engineering applications to establish a comprehensive quality-control framework covering the entire integrated die-casting process and support the reliable manufacture and service of lightweight aluminum alloy housings for high-end equipment.
Shrinkage cavities and porosity are common defects in high-temperature titanium alloy investment castings. Therefore, accurate prediction of defects and process control are crucial for casting production. Focusing on the Ti65 high-temperature titanium alloy, this study employed a numerical model coupling three-dimensional heat transfer, melt flow, and solidification to obtain the local temperature gradients and cooling rates required for experimental calibration of the critical Niyama value. Based on the experimentally observed defect distribution, the critical Niyama value of Ti65 was calibrated to 12.32 (K s) 0.5/cm. The predicted defect length differed from the experimental observation by 4.14
The addition of rare earth (RE) elements can regulate secondary phases and enhance the mechanical properties of Mg-Zn alloys through significant age-hardening effects. However, the high hot tearing tendency of Mg-Zn alloys limits their engineering applications. To address this issue, this study employed dual thermocouple differential thermal analysis testing and a T-shaped mold casting system to investigate the effects of Y, Gd, and Nd on the solidification behavior and hot tearing behavior of Mg-1Zn alloy. Meanwhile, combined with microstructural analysis and fracture morphology observation, the coupling mechanisms of various key factors on hot tearing susceptibility (HTS) were further discussed. The results show that the addition of RE elements significantly reduces alloy’s HTS, with Nd exhibiting the most prominent effect. Compared with the FR and CSC hot tearing prediction criteria, the Kou criterion can accurately reflect the variation trend of HTS, with values of 1891, 1059, 336, and 20, respectively, and the HTS coefficient decreases by 44.0
As novel high strength-ductility cast magnesium alloys, LPSO (long-period stacking order) strengthened Mg-Cu-Gd-Zr alloys still require further evaluation of their hot tearing resistance. In this work, four Mg-Cux-Gd2x-Zr0.15 (x = 0.5, 1, 1.5, 2 at
