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Be-Al alloy is a type of in situ metal matrix composite composed of a primary Be phase for strength and stiffness and a continuous Al matrix for ductility and toughness. Be-Al alloy (AlBe-Cast®910) has the characteristics of low density (2.17 g/cm3), high elastic modulus (193 GPa) and specific stiffness (88.94 GPa/(g/cm3)) as a preferred material for lightweight aerospace products. Investment casting technology can be employed to prepare the components with thin-walled complex structures for aerospace; however, the wide solidification range for Be-Al leads to difficulty in feeding a casting and results in extensive shrinkage and porosity in cast parts. In this paper, the characteristics of Be-Al alloy are introduced first. Secondly, the mechanisms of influence of adding elements on the casting process, mechanical properties (strength increases more than 20% by adding elements) and microstructure evolution are explained in detail. In addition, the heat treatment technology (strength increases at least 10% after heat treatment) and the repair of defects by electron beam welding are discussed. Finally, Be-Al alloy is a new type of composite material, and China is a major research and application country; this paper introduces its research status and analyzes existing problems and shortcomings and points out the direction of Be-Al alloy development in China in the next few years. [ABSTRACT FROM AUTHOR]

By combining first-principles calculations and experiments, the effects of Hf doping on the stability and magnetic properties of the metastable SmCo7 alloy were studied. It is found that the single TbCu7-type phase can be stabilized well by Hf doping when the Co-2e sites are occupied in the lattice structure. However, if Hf occupies the Co-3g sites, destabilization of the SmCo7 phase may occur. Moreover, Hf doping changes the partial density of states of Sm atoms in the vicinity of Co-2e sites, which causes a decrease in the net magnetic moments and hence a decrease in the saturation magnetization. The experimental results confirmed the calculation results of the phase stability and magnetic performance of the Hf-doped SmCo7 alloys. [ABSTRACT FROM AUTHOR]

Cu alloys with compositions of Cu-3.2Ni-0.7Si (wt. %) and Cu-2.8Ni-0.7Si (wt. %) were prepared by melt spinning. Effects of composition, spinning rate, aging temperature and time on microstructure, precipitation of reinforcing phases, mechanical and electrical properties of Cu–Ni–Si alloys were investigated. Melt spinning could produce continuous Cu alloy ribbons with thickness and width of the ribbons mainly dependent on the cooling rate. Columnar grains of super-saturated Cu–Ni–Si solid solutions grew in the ribbons. The melt-spun Cu–Ni–Si alloys had a faster aging kinetics in comparison with commercial alloys of similar compositions. Peak-aging of the melt spun alloys appeared after heating at 400 to 550 °C for 1 to 2 h to show maximum tensile strength of 650 to 700 MPa. Prolonged heating resulted in large precipitates on the grain boundaries and formation of precipitation-free zones around each grain with sharp drop of tensile strength. Precipitation of nano δ-Ni 2 Si rather than other phases was the main reason for the enhanced mechanical properties at peak-aging. The peak- and slightly over-aged ribbons had a good electric conductivity up to 55% IACS. • Continuous Cu alloy ribbons were prepared melt spinning. • Ni and Si dissolved in Cu to form super saturated solid solution in as-spun alloys. • The alloys showed an aging kinetics faster than commercial Cu alloys. • The alloys had a maximum tensile up to 700 MPa at peak aging. • Prolonging the aging increased electric conductivity of the alloys up to 55% IACS. [ABSTRACT FROM AUTHOR]