The Deformation Behavior, Microstructural Mechanism, and Process Optimization of PM/Wrought Dual Superalloys for Manufacturing the Dual-Property Turbine Disc

With the rapid development of modern aviation industry, dual-property turbine disc with fine comprehensive performance plays an important role in raising the thrust-to-weight ratio of the aero-engine. For manufacturing dual-property turbine disc, the powder metallurgy superalloy (PM) with excellent creep resistance was chosen as rim material, and the wrought superalloy with fine equiaxed grains was chosen as bore material. Electron beam welding was carried out on the PM/wrought dual superalloys. Hot compression tests were conducted on the PM/Wrought dual superalloys at temperatures of 1020–1140 °C and strain rates of 0.001–1.0 s−1. Deformation behavior and microstructure evolution have been investigated to study the deformation and recrystallization mechanism during hot deformation process. The results showed that PM/Wrought dual superalloy presents the similar flow behavior to single alloys and flow stress decreases significantly with the increase of deformation temperature or the decrease of strain rate. The apparent activation energy of deformation at the strain of 0.2 was determined as being 780.07 kJ·mol−1. The constitutive equation was constructed for modeling the hot deformation of PM/Wrought dual superalloy. Meanwhile, the processing map approach was further adopted to optimize the manufacturing process for the dual-property turbine disc. Additionally, a new instability criterion was proposed: the “cliff” and “valley” in the power dissipation map are determined as sufficient conditions for flow instability. The optimum processing parameter for manufacturing the PM/Wrought dual-property turbine disc can be obtained to enhance the mechanical properties, based on the analysis of processing map technology and microstructural mechanism.

Recent Studies of Surface Self-Nanocrystallization (SSNC) of Metallic Materials

Surface self-nanocrystallization (SSNC) is a new surface modification technology to develop new materials, which can obtain nanostructured layers with nanograins on the metals surface without changing the chemical composition of the metals. In this study, SSNC was introduced from the aspects of the preparation methods, microstructural mechanism, mechanical properties, surface roughness, corrosion resistance and applications. This paper will provide experience and reference for further comprehensive researches and industrial applications of SSNC.

Microstructural Analysis of Clayey Ceramics Incorporated with Fluorescent Lamp Glass Waste

The recycling of industrial wastes has become a worldwide practice owing to environmental and economical advantages. In the case of waste addition to clayey ceramics for civil construction, this sustainable practice may also bring technical benefits. Fluorescent lamps, today replacing incandescent lamps, generate typical glass waste that can improve the properties of clayey ceramics. The fluxing behavior of the glass waste contributes to the ceramic sintering mechanisms by reducing the porosity. In the present work, the effect of incorporation of 30 wt% of Hg-cleaned fluorescent lamps glass waste was investigated by means of microstructural analysis. Waste incorporated clayey ceramics, fired at 850 and 1100°C were analyzed by optical and scanning electron microscopy as well as by X-ray diffraction. The results revealed the microstructural mechanism responsible for the improvement of the ceramic properties.

Tautomeric transition between wobble A·C DNA base mispair and Watson–Crick-like A·C* mismatch: microstructural mechanism and biological significance

The A·C(w) → A·C*(WC) tautomerization via the DPT determines the origin of the spontaneous point AC/CA incorporation errors during DNA biosynthesis.