Search

In order to gain insight into how the addition of Cu element affects the crystallization mechanism of amorphous nanocrystalline alloys and soft magnetic properties, the crystallization behavior of (Fe 0.83 B 0.11 Si 0.02 P 0.03 C 0.01) 100-x Cu x (x = 0 and 0.5) amorphous ribbons was investigated based on kinetic and thermodynamic behavior under non-isothermal and isothermal annealing conditions. The results show that under non-isothermal annealing conditions, the Cu0.5 amorphous ribbon not only favors the formation of the amorphous structure, but also enlarges the temperature window for annealing and improves the thermal stability of the α-Fe(Si) phase. At the same time, the Cu0.5 amorphous ribbon shows slow kinetic and is insensitive to heating rate change during annealing treatment. Under isothermal conditions, the addition of Cu decreases the nucleation activation energy (E n) and increases the growth activation energy (E g). This further indicates that the nucleation of α-Fe(Si) grains is easier than the growth process, which is conducive to the formation of a homogeneous nanostructure and improves the soft magnetic properties of the alloy. Compared to Cu0 amorphous ribbon, it is also shown that the Cu0.5 amorphous ribbon changes the crystallization mechanism from diffusion-controlled one-dimensional to two-dimensional growth when the crystallization volume fraction x is 10–30 vol%. While three-dimensional growth become dominated when x is reaches 60 vol% for both ribbons. Therefore, the kinetics of crystallization as well as microstructure supports that the Cu0.5 ribbon is able to exhibit uniformly fine nanocrystalline structures. Further, the Cu0.5 nanocrystalline ribbon shows a higher B s of 1.85 T and a lower H c of 2.55 A/m, respectively, and the favorable (100) orientation of α-Fe(Si) grains formed after annealing is another factor to increase B s. • The Cu-containing alloy show kinetic insensitivity and is suitable for a high heating rate. • The addition of Cu changes the crystallization mechanism when x is between 10% and 30%. • When the applied magnetic field is ND, precipitation of (100) orientation α-Fe grains favors enhancing B s. • The Cu0.5 alloy show B s of 1.85 T, H c of 2.55 A/m. [ABSTRACT FROM AUTHOR]

• The Cu 6 Sn 5 and Cu 3 Sn alloy interface layers are prepared through simple temperature control. • The key factors affecting the interface layer of Li metal in different Cu-Sn alloys have been summarized. • Cu 6 Sn 5 @Cu has a uniform surface structure and excellent electrolyte wettability. • The deposition mechanisms of Li metal on the Cu 6 Sn 5 and Cu 3 Sn alloy interface layer are proposed. [Display omitted] Lithium (Li) metal is one of the best anode candidates for high energy density battery because of the lowest electrode potential and high theoretical capacity. However, the unstable electrode/electrolyte interface will cause uneven Li deposition and induce the formation of Li dendrites. The Cu-Sn alloy interface layer has been proven to be an effective strategy to inhibit the growth of Li dendrites, but how the alloy type of Cu-Sn alloy affects the deposition/exfoliation behavior of Li metal is still unclear. Here, we used a simple and fast chemical plating method to prepared lithophilic Cu 3 Sn and Cu 6 Sn 5 pure phase interface layers on the surface of the Cu foil by controlling the temperature. Then, the effects of two different alloy types on the deposition/stripping behavior of Li metal anodes were studied. Compared with Cu 3 Sn@Cu, Cu 6 Sn 5 @Cu has a more uniform surface structure and higher surface free energy. Uniform electron distribution and fast reaction kinetics are conducive to the uniform deposition of Li metal. Meanwhile, Cu 6 Sn 5 @Cu also has higher electrolyte wettability. This helps to reduce the interphase impedance and polarization, thereby avoiding the growth of Li dendrites. These advantages make deposition mechanism of Li metal on the Cu 6 Sn 5 @Cu surface a unidirectional "Parallel-Deposition", while on the Cu 3 Sn@Cu surface it is a multi-directional "Preferred-Deposition". After being modified by Cu 6 Sn 5 , a more reasonable deposition mechanism reduces the overpotential of Li deposition on Cu foil by half. Even under the high deposition capacity of 10 mAh cm−2, Cu 6 Sn 5 @Cu can still cycle stably for more than 900 h. In addition, Li-Cu 6 Sn 5 @Cu has also been proved to have more stable rate performance and higher capacity retention rate than Li-Cu 3 Sn@Cu when it is used in full cell with LiFePO 4. [ABSTRACT FROM AUTHOR]

Abstract: Using CaCO3 as blowing agent and via melt foaming method, Mg foams with closed-cells have been fabricated successfully. It has been proved that the blowing gas to foam melted Mg is not CO2 but CO, which is released from the liquid–solid reaction between Mg and CaCO3. The releasing temperature of CO is more than 100°C lower than the decomposition temperature of CaCO3, which leads to melted Mg being foamed much more easily and the foaming process can be accomplished in a temperature range of 665–750°C. [Copyright &y& Elsevier]