Xingguang Liu

Bio: Xingguang Liu is an academic researcher from University of Sheffield. The author has contributed to research in topics: Coating & Sputter deposition. The author has an hindex of 7, co-authored 9 publications receiving 545 citations.

Segregation mediated heterogeneous structure in a metastable β titanium alloy with a superior combination of strength and ductility

Abstract: In β titanium alloys, the β stabilizers segregate easily and considerable effort has been devoted to alleviate/eliminate the segregation. In this work, instead of addressing the segregation problems, the segregation was utilized to develop a novel microstructure consisting of a nanometre-grained duplex (α+β) structure and micrometre scale β phase with superior mechanical properties. An as-cast Ti-9Mo-6W alloy exhibited segregation of Mo and W at the tens of micrometre scale. This was subjected to cold rolling and flash annealing at 820 oC for 2 and 5 mins. The solidification segregation of Mo and W leads to a locally different microstructure after cold rolling (i.e., nanostructured β phase in the regions rich in Mo and W and plate-like martensite and β phase in regions relatively poor in Mo and W), which play a decisive role in the formation of the heterogeneous microstructure. Tensile tests showed that this alloy exhibited a superior combination of high yield strength (692 MPa), high tensile strength (1115 MPa), high work hardening rate and large uniform elongation (33.5%). More importantly, the new technique proposed in this work could be potentially applicable to other alloy systems with segregation problems.

Exploring the mechanism of "Rare Earth" texture evolution in a lean Mg-Zn-Ca alloy.

Abstract: The entire recrystallisation sequence and associated crystallographic texture evolution of Mg-0.8Zn-0.2Ca (wt.%) alloy was tracked using a quasi-in-situ electron backscatter diffraction (EBSD) method. Characteristic “Rare Earth” (RE) texture was formed, originating mainly from double twins and twinning-related shear bands consisting of compression and double twins. The RE textures appeared during the nucleation stage and were preserved during the relative uniform grain growth period because of solute segregation and concurrent precipitation although the alloying element content was very low. Ca and Zn co-segregated along grain boundaries with no evidence that segregation was preferred along special types of grain boundaries. The interactions between deformation microstructures, concurrent precipitation, solute drag, grain growth and texture evolution are discussed in detail. All the results indicate that Ca performs a similar role to that of RE elements in forming RE texture.

An overview of photocatalytic degradation: photocatalysts, mechanisms, and development of photocatalytic membrane

Abstract: Photocatalysis is an ecofriendly technique that emerged as a promising alternative for the degradation of many organic pollutants. The weaknesses of the present photocatalytic system which limit their industrial applications include low-usage of visible light, fast charge recombination, and low migration ability of the photo-generated electrons and holes. Therefore, various elements such as noble metals and transition metals as well as non-metals and metalloids (i.e., graphene, carbon nanotube, and carbon quantum dots) are doped into the photocatalyst as co-catalysts to enhance the photodegradation performance. The incorporation of the co-catalyst which alters the photocatalytic mechanism was discussed in detail. The application of photocatalysts in treating persistent organic pollutants such as pesticide, pharmaceutical compounds, oil and grease and textile in real wastewater was also discussed. Besides, a few photocatalytic reactors in pilot scale had been designed for the effort of commercializing the system. In addition, hybrid photocatalytic system integrating with membrane filtration together with their membrane fabrication methods had also been reviewed. This review outlined various types of heterogeneous photocatalysts, mechanism, synthesis methods of biomass supported photocatalyst, photocatalytic degradation of organic substances in real wastewater, and photocatalytic reactor designs and their operating parameters as well as the latest development of photocatalyst incorporated membrane.

Optimization strategies of composite phase change materials for thermal energy storage, transfer, conversion and utilization

Abstract: Thermal energy harvesting technologies based on composite phase change materials (PCMs) are capable of harvesting tremendous amounts of thermal energy via isothermal phase transitions, thus showing enormous potential in the design of state-of-the-art renewable energy infrastructure. Great progress has been recently made in terms of enhancing the thermal energy storage capability, transfer rate, conversion efficiency and utilization of composite PCMs. Although there are some recent reviews on composite PCMs, they are mainly concentrated on the thermal transfer enhancement and conventional utilization of PCMs. There are few systematic reviews concerning optimization strategies of PCM for thermal energy conversion. In particular, advanced multifunctional utilization of PCMs is still in its infancy. Herein, we systematically summarize the optimization strategies and mechanisms of recently reported composite PCMs for thermal energy storage, thermal transfer, energy conversion (solar-to-thermal, electro-to-thermal and magnetic-to-thermal conversion) and advanced utilization (fluorescence emission, infrared stealth technologies, drug release systems, thermotherapy and thermal protection), including some novel supporting materials (BN nanosheets and metal organic frameworks (MOFs)). Simultaneously, we provide in-depth and constructive insights into the correlations between the structural optimization strategies and thermal performances of composite PCMs. Finally, future research trends, alternative strategies and prospects are also highlighted according to up-to-date optimization strategies.