The Al-Si-Cr-Co-Ni High Entropy Alloy (HEA) with low density (about 5.4 g/cm³) and excellent performance had significant potential in the lightweight engineering material field. To further research and optimize the Al-Si-Cr-Co-Ni system HEA, the influences of element Cr on the microstructures and performances of lightweight AlSi_0.5Cr_xCo_0.2Ni (in mole ratio, x = 1.0, 1.2, 1.4, 1.6, and 1.8) HEAs were investigated. The experiment results manifested that AlSi_0.5Cr_xCo_0.2Ni HEAs were composed of A2 (Cr-rich), B2 (Ni-Al), and Cr₃Si phases, indicating that the addition of Cr did not result in the formation of a new phase. However, ample Cr increased the Cr₃Si phase composition, further ensuring the high hardness (average HV 981.2) of HEAs. Electrochemical tests demonstrated that HEAs with elevated Cr₃Si and A2 phases afforded greater corrosion resistance, and the improvement in corrosion was more pronounced when x > 1.6. This work is crucial in the development of lightweight engineering HEAs, which are of tremendous practical utility in the fields of cutting tools, hard coating, etc.

High-entropy alloys (HEAs) were prepared with strong antioxidant metals Al, Cr, Ti, and Si as matrix elements, and the effects of rare earth (RE) lanthanum (La) and yttrium (Y) doping on their microstructures and high-temperature oxidation resistance were explored in this study. The AlCrTiSi_0.2RE_0.02 HEAs were prepared by using vacuum arc melting and were oxidized mass gain at 1000 °C. After oxidation for 53 h, AlCrTiSi_0.2 HEA had a mass increase of 1.195 mg/cm², and it had the best oxidation resistance of three HEAs (AlCrTiSi_0.2, AlCrTiSi_0.2La_0.02, and AlCrTiSi_0.2Y_0.02). The surface oxide layers of three HEAs mainly consisted of Al and Ti oxides; the layered oxide film of AlCrTiSi_0.2 alloy was mainly composed of dense Al₂O₃, and the acicular oxide films of AlCrTiSi_0.2La_0.02 and AlCrTiSi_0.2Y_0.02 alloys were primarily composed of loose Ti oxide. Doping La and Y decreased the oxidation resistance of AlCrTiSi_0.2. In the early stage of oxidation of rare earth HEAs, the surface oxide layer was loose because La and Y reacted with the matrix metal, which slowed down the diffusion of element Al or accelerated the diffusion of element Ti. In the late stage of oxidation, La and Y interacted with O and entered the matrix metal to form rare earth oxides.

With the rapid development of new energy fields and the current shortage of lithium supply, an efficient, clean, and stable lithium resource extraction process is urgently necessary. In this paper, various advanced detection methods were utilized to conduct a mineralogical analysis of the raw ore and systematically study the occurrence state of lithium; the limestone sintering process was strengthened and optimized, elucidating the sintering mechanism and analyzing the leaching process kinetics. Under an ingredient ratio of 1:3, a sample particle size of 300 mesh, a sintering temperature of 1100 °C, a sintering time of 3 h, a liquid–solid ratio of 2:1, a leaching temperature of 95 °C, and a leaching time of 1 h, the leaching rate of Li reached 90.04%. The highly active Ca–O combined with Si–O on the surface of β–spodumene to CaSiO₄, and Al–O was isolated and combined with Li to LiAlO₂, which was beneficial for the leaching process. The leaching process was controlled by both surface chemical reactions and diffusion processes, and Ea was 27.18 kJ/mol. These studies provide theoretical guidance for the subsequent re-optimization of the process.