Nanocrystalline (NC) structure can lead to the considerable strengthening of metals and alloys. Obtaining appropriate comprehensive mechanical properties is always the goal of metallic materials. Here, a nanostructured Al-Zn-Mg-Cu-Zr-Sc alloy was successfully processed by high-pressure torsion (HPT) followed by natural aging. The microstructures and mechanical properties of the naturally aged HPT alloy were analyzed. The results show that the naturally aged HPT alloy primarily consists of nanoscale grains (~98.8 nm), nano-sized precipitates (20–28 nm in size), and dislocations (1.16 × 1015 m−2), and exhibits a high tensile strength of 851 ± 6 MPa and appropriate elongation of 6.8 ± 0.2%. In addition, the multiple strengthening modes that were activated and contributed to the yield strength of the alloy were evaluated according to grain refinement strengthening, precipitation strengthening, and dislocation strengthening, and it is shown that grain refinement strengthening and precipitation strengthening are the main strengthening mechanisms. The results of this study provide an effective pathway for achieving the optimal strength–ductility match of materials and guiding the subsequent annealing treatment.

Transition metal selenides (TMSs) have been widely believed as promising anode materials for sodium-ion batteries (SIBs). Element doping is a promising but ambiguous strategy to further enhance sodium storage performance due to the complexity of doping conditions and the sensitivity of the selenization process. Herein, tellurium (Te) is selected to fabricate Te-doped nickel cobalt selenide (Te-NiCoSe) using a melting method. Besides the common merit of expanding the interplanar space of NiCoSe, the melted Te can also result in a "size splitting effect" to decrease the particle size of bulk NiCoSe, exposing more surface active sites and accelerating the intercalation/deintercalation reaction kinetics. In addition, the introduction of Te can also inhibit the "reduction effect" of the selenization process induced by high temperature, which results in the charge redistribution of NiCoSe, stabilizing the electronic structure. As a result, the fabricated Te-NiCoSe exhibits a high reversible capacity of 448.7 mA h g(-1) at 1 A g(-1), a superior rate capacity of 324.9 mA h g(-1) at 30 A g(-1), and an outstanding capacity retention rate of 88.5% after 1000 cycles at 20 A g(-1).

The strategy of preparing a CO2RR catalyst on the basis of solid-phase exfoliation helps to fully expose the catalytic centers of Ni and Fe, and provides a channel for proton transfer, so that the catalyst exhibits excellent performance.

发展环境友好和成本低廉的析氢催化剂对于可再生能源技术具有重要意义.采用二茂铁和聚乙烯吡咯烷酮(PVP)为原料,通过简单的水热法结合尿素辅助下的高温热解合成碳化铁/氮掺杂碳(Fe3 C/N-C)的复合纳米粒子.重点比较了不同热解温度对所制备的复合纳米粒子的成分、微观结构以及电催化析氢性能的影响.结果表明,在800℃热解温度下获得的Fe3C/N-C在碱性电解液中具有最好的催化活性,其过电位为211 mV(电流密度为10 mA/cm2),塔菲尔斜率仅137 mV/dec,优于其他热解温度下获得的样品,且该样品连续工作10 h后催化活性未见明显衰减,展现了良好的耐久性.该工作将为过渡金属碳化物和氮掺杂碳的复合结构调控提供新思路,同时为发展高效廉价的非贵金属电催化剂提供技术支撑.

采用真空电弧熔炼法制备了Al0.8 CrFe2 Nix高熵合金(x为Ni与Cr的摩尔比),采用金相观察、X射线衍射、显微硬度检测和压缩试验等手段研究了Ni含量对其组织及力学性能的影响.结果 表明,当x=0.50时,合金为B2 +BCC晶体结构,组织为树枝晶十胞状晶;当x=1.25时,合金晶体结构转变为单一的BCC结构,而组织变为单一的树枝晶;当x=2.00时,合金转变为FCC+ BCC的混合结构,其组织转变为细小密集的片层状共晶组织;随着Ni含量继续增加,当x=2.75时,合金保持着FCC+ BCC结构,而FCC相比例明显增加,并形成了完整连贯的树枝晶组织;Al0.8 CrFe2Nix高熵合金的硬度随x的增加而降低,同时屈服强度减小、韧性增加.

The microstructure difference of the Co-Cr alloys fabricated by a cast technique and a SLM (selective laser melting) technique is investigated,and the reasons causing the different microstructures and the effects of the different microstructures on the properties of the Co-Cr alloys are discussed.The Co-Cr alloy powder and bulk with similar compositions are selected to prepare Co-Cr samples using the SLM technique and the cast technique,respectively.The microstructures of the fabricated Co-Cr samples are investigated by SEM and the chemical compositions of featured areas are analyzed by EDX.The microstructure of the Co-Cr alloy fabricated by the SLM technique is uniform without phase separation.However,the phase separation rich in Mo element is found in the Co-Cr alloys fabricated by both the centrifugal cast technique and the vacuum cast technique.The Co-Cr samples fabricated by the SLM technique and the cast technique both contain less pores.In conclusion,the quality of the Co-Cr alloy fabricated by the SLM technique is better than the cast technique.

采用一种无模板的化学气相沉积法裂解金属有机物,以二茂铁为催化剂,二甲苯为碳源,利用单温炉加热装置在100 min内成功制备了2.7 mm超长定向碳纳米管阵列,生长速率高达27 μm·min-1.运用扫描电子显微镜、透射电子显微镜、拉曼光谱对定向碳纳米管阵列进行形貌观察和表征,结果表明:制得的碳纳米管阵列具有优越的定向性和管结构,并且石墨化程度高.给出了快速生长超长定向碳纳米管阵列的优化制备条件,结合表征结果讨论了碳纳米管阵列的生长机制,认为超长碳纳米管阵列采用的是一种催化剂固定不动的开口生长方式,碳源和催化剂的连续供应保证了超长碳纳米管阵列的快速生长.