摘要：From the perspective of biomechanics and forming technology,Ti−Fe−Zr−Sn−Y eutectic alloy was designed using a“cluster-plus-glue-atom”model,and then the alloy was prepared by laser additive manufacturing(LAM)on pure titanium *** mechanical properties of the alloy were evaluated using micro-hardness and compression tester,and the elastic modulus was measured by *** results show that the alloy exhibits a high hardness of HV(788±10),a high strength of 2229 MPa,a failure strain of 14%,and a low elastic modulus of 87.5 *** alloy also has good tribological,chemical,forming,and biological *** comprehensive performances of the Ti64.51Fe26.40Zr5.86Sn2.93Y0.30 alloy are superior to those of the Ti70.5Fe29.5 eutectic alloy and commercial Ti−6Al−4V *** the above-mentioned qualities make the alloy a promising candidate as LAM biomaterial.

摘要：Ti−Al−V−Nb alloys with the cluster formula,12[Al−Ti_(12)](AlTi_(2))+5[Al−Ti1_(4)](V,Nb)2Ti,were designed by replacing V with Nb based on the Ti−6Al−4V ***-track cladding layers and bulk samples of the alloys with Nb contents ranging from 0 to 6.96 wt.%were prepared by laser additive manufacturing to examine their formability,microstructure,and mechanical *** single-track cladding layers,the addition of Nb increased the surface roughness slightly and decreased the molten pool height to improve its *** alloy,Ti−5.96Al−1.94V−3.54Nb(wt.%),exhibited better geometrical accuracy than the other alloys because its molten pool height was consistent with the spread layer thickness of the *** microstructures of the bulk samples contained similar columnar β-phase grains,regardless of Nb *** grains grew epitaxially from the Ti substrate along the deposition direction,with basket-weaveα-phase laths within the columnar ***α-phase size increased with increasing Nb contents,but its uniformity *** the deposition direction,the Vickers hardness increased from the substrate to the *** Ti−5.96Al−1.94V−3.54Nb alloy exhibited the highest Vickers hardness regardless of deposition position because of the optimal matching relationship between theα-phase size and its content among the designed alloys.

摘要：Rechargeable Li-O2 batteries have attracted considerable interests because of their exceptional energy density. However, the short lifetime still remained as one of the bottle-neck obstacles for the practical application of rechargeable Li-O2 batteries. The development of efficient cathode catalyst is highly desirable to reduce the energy barrier of Li-O2 reaction and electrode failure. In this work, we report a facile strategy for the fabrication of a high-per- formance cathode catalyst for rechargeable Li-O2 batteries by the encapsulation of high content of active Fe nanorods into N-doped carbon nanotubes with high stability （denoted as Fe@NCNTs）. First-principles calculations reveal that the synergistic charge transfer and redistribution between the interface of Fe nanorods, the CNT walls and the active N dopants greatly facilitate the chemisorption and subsequent dissociation of O2 molecules into the epoxy intermediates on the carbon surface, which benefits the uniform growth of nanosized discharge products on CNT surface and thus boosts the reversibility of Li-O2 reactions. As a result, the cathode with Fe@NCNT catalyst exhibRs long cycling sta- bility with high capacities （1000 mA h g-1 for 160 cycles and 600 mA h g-t for 270 cycles）. Based on the total mass of Fe@NCNTs ＋ Li2O2, high gravimetric energy densities of 2120-2600 W h kg-~ can be achieved at the power densities of 50-795 W kg-1.

摘要：Understanding the temperature-dependent hardness of covalent materials is of fundamental scientific interest and crucial technical *** we propose a temperature-dependent hardness formula for zinc-blende structured covalent materials based on the dislocation *** results indicate that at low temperatures,the Vickers hardness is primarily modulated by Poisson’s ratio and the shear modulus,with the latter playing a dominant *** an increase in temperature,the governing mechanism for the plastic deformation switches from shuffle-set dislocation control to glide-set dislocation control,and the hardness decreases precipitously at elevated ***,the intrinsic parameter a3G is revealed for zinc-blende structured covalent materials,which represents the resistance of a material to softening at high *** temperaturedependent hardness model agrees remarkably well with the experimental data of zinc-blende structured covalent *** work not only sheds light on the physical origin of hardness,but also provides a practical guide for the design of superhard materials.

摘要：Low cost,high strength and high elongation steel is always the major trends of steel development especially for automotive ***,raising strength usually brings about loss of ductility,which is known as the strength-ductility trade-off[1].Solving strength-ductility trade-off by increasing low cost carbon content is the century-long pursuit of ***[2]pointed out that investigation since 1900s indicates that the increase of carbon content leads to enhancing strength,but deteriorating ductility and other properties of steels.

摘要：The effects of TiB_(2) and Zr on the microstructure,aging response and mechanical properties of hot-extruded Al-Zn-Mg-Cu based materials were investigated and compared by multi-scale microstructure characterization *** results showed that proper addition of TiB_(2) particles could refine grain size during solidification,promote dynamic recrystallization during extrusion,and inhibit grain growth during solution ***,Zr addition had minor influence on the grain refinement during solidification,but could effectively suppress recrystallization and grain growth compared with the Zr-free ***,the TiB_(2) addition could simultaneously enhance the aging kinetics and peak-aged hardness of the ***,Zr addition could also improve the peak-aged hardness with minor effect on the aging kinetics of the ***,the quench sensitivity,elastic modulus and tensile properties of the materials were compared and ***,the relationship between the microstructure and mechanical properties,and the strengthening mechanisms were discussed in detail.

摘要：Each conventional alloy has its own specific compositions but the compositional origin is largely unknown due to our insufficient understanding about chemical shortrange ordering in the alloy,in particular,in the solid-solution *** the present paper,the compositions of metallic alloys are discussed and formulated,by unveiling the basic moleculelike structural units in solid *** oscillation theory,which describes the partial charge screening behavior in solid solutions,and henceforth the origin of short-range ordering,is applied to pin down the ideal chemical compositions of conventional metallic *** propose that,at a specific composition,atoms self-assemble into an ideally ordered structure consisting of atoms residing in the nearestneighbor shell(denoted as cluster)plus those in the next outer shell(denoted as glue atoms),which can be formulated as[cluster](glue atoms).This simplified version of short-rangeorder structure represents the smallest charge-neutral and mean-density zone(termed as“chemical units”)and can be regarded as the‘molecules’of solid ***,the chemical units and the corresponding molecule-like formulas for face-centered-cubic(FCC),hexagonal close-packed(HCP),and body-centered cubic(BCC)structures are analyzed and equations are obtained to identify the chemical formulas for FCC solid *** instance,well-knownα-brass Cu-30 Zn alloy is formulated as[Zn-Cu_(12)]*** of aluminum alloys,superalloys and stainless steels are also illustrated,demonstrating the versatility of the present model to interpret chemically complex alloys.

摘要：Photoredox catalysis has become an indispensable solution for the synthesis of small organic ***,the precise construction of single-atomic active sites not only determines the catalytic performance,but also avails the understanding of structure–activity ***,we develop a facile approach to immobilize single-atom Ni sites anchored porous covalent organic framework(COF)by use of 4,4',4''-(1,3,5-triazine-2,4,6-triyl)trianiline and 2,6-diformylpyridine(Ni SAS/TD-COF).Ni SAS/TDCOF catalyst achieves excellent catalytic performance in visible-light-driven catalytic carbon–nitrogen cross-coupling reaction between aryl bromides and amines under mild *** reaction provides amine products in excellent yields(71%–97%)with a wide range of substrates,including aryl and heteroaryl bromides with electron-deficient,electron-rich and neutral ***,Ni SAS/TD-COF could be recovered from the reaction mixture,corresponding to the negligible loss of photoredox performance after several *** work provides a promising opportunity upon rational design of single-atomic active sites on COFs and the fundamental insight of photoredox mechanism for sustainable organic transformation.