Kinetics of Glass Transition and Crystallization in Carbon Nanotube Reinforced Mg-Cu-Gd Bulk Metallic Glass

Mg65Cu25Gd10 bulk metallic glass and its carbon nanotube reinforced composite were prepared. Differential scanning calorimeter （DSC） was used to investigate the kinetics of glass transition and crystallization processes. The influence of CNTs addition to the glass matrix on the glass transition and crystallization kinetics was studied. It is shown that the kinetic effect on glass transition and crystallization are preserved for both the monothetic glass and its glass composite. Adding CNTs in to the glass matrix reduces the influence of the heating rate on the crystallization process. In addition, the CNTs increase the energetic barrier for the glass transition. This results in the decrease of GFA. The mechanism of the GFA decrease was also discussed.

Microstructure and mechanical properties of Zr-Cu-Al bulk metallic glasses

Zr49Cu46Al5 and Zr48.5Cu46.5Al5 bulk metallic glasses(BMGs) with diameter of 5 mm were prepared through water-cooled copper mold casting. The phase structures of the two alloys were identified by X-ray diffractometry(XRD). The thermal stability was examined by differential scanning calorimetry(DSC). Zr49Cu46Al5 alloy shows a glass transition temperature, Tg, of about 689 K, an crystallization temperature, Tx, of about 736 K. The Zr48.5Cu46.5Al5 alloy shows no obvious exothermic peak. The microstructure of the as-cast alloys was analyzed by transmission electron microscopy(TEM). The aggregations of CuZr and CuZr2 nanocrystals with grain size of about 20 nm are observed in Zr49Cu46Al5 nanocrystalline composite, while the Zr48.5Cu46.5Al5 alloy containing many CuZr martensite plates is crystallized seriously. Mechanical properties of bulk Zr49Cu46Al5 nanocrystalline composite and Zr48.5Cu46.5Al5 alloy measured by compression tests at room temperature show that the work hardening ability of Zr48.5Cu46.5Al5 alloy is larger than that of Zr49Cu46Al5 alloy.

Preparation of Cu-based Bulk Metallic Glass Matrix Composites

Cu47Ti34Zr11Ni8 bulk metallic glass （BMG） matrix composites containing in situ formed TiC particles and 5-TiCu dendrite phase were developed by copper mold cast. The thermal stability and microstructure of the composites are investigated. Room temperature compression tests reveal that the composite samples exhibit higher fracture strength and distinct plastic strain of 0.2%-0.5%, comparing with that of the corresponding Cu47Ti34Zr11Ni8 monolithic BMG.

Supramolecular Macrocycle Regulated Single-Atom MoS_(2)@Co Catalysts for Enhanced Oxygen Evolution Reaction

The development of active water oxidation catalysts for water splitting has stimulated considerable interest.Herein,the design and building of single atom Co sites using a supramolecular tailoring strategy are reported,that is,the introduction of pillar[4]arene[1]quinone(P4A1Q)permits mononuclear Co species stereoelectronically assembled on MoS_(2)matrix to construct an atomically dispersed MoS_(2)@Co catalyst with modulated local electronic structure,definite chemical environment and enhanced oxygen evolution reaction performance.Theoretical calculations indicate that immsobilized single-Co sites exhibit an optimized adsorption capability of oxygen-containing intermediates,endowing the catalyst an excellent electrocatalytic oxygen evolution reaction activity,with a low overpotential of 370 mV at 10 mA cm^(-2)and a small Tafel slope of 90 mV dec^(-1).The extendable potential of this strategy to other electrocatalysts such as MoS_(2)@Ni and MoS_(2)@Zn,and other applications such as the hydrogen evolution reaction was also demonstrated.This study affords new insights into the rational design of single metal atom systems with enhanced electrocatalytic performance.

Microstructure and mechanical properties of a novel Zr-based bulk metallic glass composite

Zr48.5Cu46.5Al5 bulk metallic glass (BMG) com- posites with diameters of 3 and 4 mm were prepared through suction casting in an arc melting furnace by modulating the alloy composition around the monothetic BMG composition of the high glass forming ability. Microstructural charac- terization reveals that the composites contain micron-sized CuZr phase with martensite structure, as well as nano-sized Zr2Cu crystalline particles and Cu10Zr7 plate-like phase em- bedded in an amorphous matrix. Room temperature com- pression tests showed that the composites exhibited signifi- cant strain hardening and obvious plastic strain of 7.7% for 3 mm and 6.4% for 4 mm diameter samples, respectively.

Supercritical CO2-induced room-temperature ferromagnetism in two-dimensional MoO3−x

Two-dimensional(2D)magnetic semiconductors are crucial in spin-based information-processing technologies due to the combination of the strong 2D quantum effects,surface effects and the control of spin states.However,most experimental approaches for tuning 2D magnets achieve pure ferromagnetism at low temperature.Herein,a defect engineering strategy using supercritical CO2 is introduced to achieve nanostructure with abundant defects for 2D MoO3−x,and room-temperature ferromagnetism can be obtained and tuned by introduction of the Mo5+ion depending on the change of supercritical pressure.In defective regions,the presence of the pentacoordinated[Mo5+O5]centers can achieve ferromagnetic ordering resulting in room-temperature ferromagnetism.With increasing supercritical pressure,it is easier for the supercritical CO2 to break the Mo–O bonds,achieving enhancement of the ferromagnetic performance with desired Curie temperature(>380 K).The magnetic responses in the MoO3−x system provide a step closer to the expansion of spin electronics.