Evaluation on elevated-temperature stability of modified 718-type alloys with varied phase configurations

Inconel 718 is a Ni–Fe-based superalloy widely used in aerospace engines because of its excellent mechanical properties.However,the inferior stability of theγ″phase limits the application of Inconel 718,which coarsens rapidly at temperatures greater than 650°C.Further improving the temperature tolerance of Inconel 718 requires optimization of the phase configuration via modification of the alloy’s chemical composition.Given the aforementioned objective,this work was conducted to study the precipitation behavior and thermal stability of the strengthening phases with various structures in modified Inconel 718 alloys by tailoring the Al/Ti ratio.With increasing Al/Ti ratio,three particle configurations were formed:γ′/γ″composite,isolatedγ′,andγ′/γ″/γ′composite particles.The results of aging tests demonstrate that the isolatedγ′and theγ′/γ″/γ′composite structure exhibited better thermal stability at temperature as high as 800°C.The isolatedγ′exhibited a reduced coarsening rate compared with theγ′/γ″/γ′composite particles because the isolatedγ′phase was rich in Al,Ti,and Nb.However,theγ′/γ″composite particles coarsened and decomposed rapidly during aging at temperatures greater than 700°C because of the lower stability resulting from the larger number ofγ″particles.The obtained results provide necessary data for the compositional optimization of novel 718-type alloys.

Scalable synthesis of nanoporous high entropy alloys for electrocatalytic oxygen evolution

High entropy alloys(HEAs)containing five or more equimolar components have shown promising catalytic performance due to their unique chemical and mechanical properties.However,it is still challenging to prepare scalable and efficient nanoporous HEAs as catalysts.Here,we present a facile strategy to synthesize largescale nanoporous HEAs particles by combing vacuum induction melting,gas atomization,and acidic etching procedure.The application of HEAs to energy conversion is evaluated with electrocatalytic oxygen evolution reaction(OER)on AlCrCuFeNi HEAs.The HEAs exhibit a low OER overpotential of 270 mV to achieve a current density of 10 mA·cm^(-2),a small Tafel slope of 77.5 mV·dec^(-1),and long-term stability for over 35 h in 1 mol·L^(-1) KOH,which is comparable to the state-of-the-art OER electrocatalyst RuO2.The findings in this paper not only provide an industrial approach to produce nanoporous HEAs powder but also inspire the applications of HEAs as catalysts.

Scalable synthesis of mesoporous FeS_(2) nanorods as highperformance anode materials for sodium-ion batteries

Sodium-ion batteries(SIBs),as highly promising alternatives to lithium-ion batteries(LIBs),can be widely used in a variety of next-generation energy storage systems.However,the current commercial graphite anodes of LIBs could not intercalate sodium ions to appreciable extent,and the electrochemical irreversibility hinders further application.Searching for a suitable anode material is a critical issue for the successful development of SIBs.Herein,we report a convenient,fast,and large-scale preparation method of mesoporous FeS_(2) nanorods.Our specially designed one-dimensional mesoporous structure of FeS_(2) takes full advantage of ultra-high strain relaxation as well as fast Na^(+)transport rate arising from microstructural characteristics.As a result,the mesoporous FeS_(2) nanorods exhibited excellent sodium storage performance.The discharge capacity was retained at 711.1 mAh·g^(-1) after 450 cycles at a current density of 1000 mA·g^(-1).The special microstructure and superior performance of mesoporous FeS_(2) nanorods represent a critical step for transition metal sulfides electrode materials toward practical SIBs application.

Deviating from the nanorod shape： Shape-dependent plasmonic properties of silver nanorice and nanocarrot structures

Noble metallic nanostructures exhibit special optical properties resulting from excitation of surface plasmons. Among the various metallic nanostructures, nanorods have attracted particular attention because of their unique and intriguing shape-dependent plasmonic properties. Nanorods can sup- port transverse and longitudinal plasmon modes, the latter ones depending strongly on the aspect ratio of the nanorod. These modes can be routinely tuned from the visible to the near-infrared spectral regions. Although nanorods have been investigated extensively, there are few studies de- voted to nanostructures deviating from the nanorod shape. This review provides an overview of recent progress in the development of two kinds of novel quasi-one-dimensional silver nanostruc- tures, nanorice and nanocarrot, including their syntheses, crystalline characterizations, plasmonic property analyses, and performance in plasmonic sensing applications.