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Start Over Author "Feng, Zhihao" Publisher elsevier bv
47 results on '"Feng, Zhihao"'

14. Origins of low lattice thermal conductivity in 2D carbon allotropes

Author

Dayong Wu, Feng Zhihao, Zhibo Zhang, Jie Kang, Jianhui Li, Ru Su, Dong Huicong, and Qian Wang

Subjects
lcsh:TN1-997, Materials science, Phonon, chemistry.chemical_element, Phonon mean free path, 02 engineering and technology, 01 natural sciences, law.invention, Biomaterials, Molecular dynamics, Thermal conductivity, law, 0103 physical sciences, Thermal, Bond difference parameter, lcsh:Mining engineering. Metallurgy, 010302 applied physics, Graphene, Metals and Alloys, 021001 nanoscience & nanotechnology, Thermal conduction, Surfaces, Coatings and Films, chemistry, Chemical bond, Chemical physics, Phonon group velocity, Carbon allotropes, Ceramics and Composites, 0210 nano-technology, Carbon, Thermal transmission
Abstract

Absract Carbon allotropes occupy significant roles in heat conduction fields. The thermal transmission in most allotropes is determined by phonons, and ultimately, fundamentally is dependent on the properties of chemical bonds. In this paper, thermal transmission in four novel 2D carbon allotropes has been studied, including penta-graphene, Ψ-graphene, pop-graphene and net-W by using non-equilibrium molecular dynamic (NEMD) simulations and time domain normal mode analysis (TDNMA). Graphene, the standard 2D carbon allotrope, has also been examined for comparison. Our NEMD simulated results indicate that despite of the same dimension, they possess significantly different thermal properties than that of graphene: their thermal conductivities show about 85%–95% reduction of that for graphene at room temperature. TDNMA shows that the lower thermal conductivity of penta-graphene, Ψ-graphene, pop-graphene and net-W is caused by the combined action of their reduced phonon group velocities and relaxation time. Moreover, the bond difference parameter has also been applied to describe the relationship between bond properties and thermal transmission in sp2 composed carbon allotropes.

Published
2021

24. Utilizing a novel modifier to realize multi-refinement and optimized heat treatment of A356 alloy

Author

Jie Kang, Dayong Wu, Feng Zhihao, Ru Su, Tian Li, Liu Chunhai, and Wang Lisheng

Subjects
Materials science, Mechanical Engineering, Alloy, Metals and Alloys, Intermetallic, 02 engineering and technology, engineering.material, 010402 general chemistry, 021001 nanoscience & nanotechnology, Microstructure, 01 natural sciences, Grain size, 0104 chemical sciences, Grain growth, Mechanics of Materials, Ultimate tensile strength, Materials Chemistry, engineering, Grain boundary, Composite material, 0210 nano-technology, Eutectic system
Abstract

Al-5Sr-8Ce master alloy was fabricated as a novel modifier, and its effect on the microstructure and tensile properties of A356 alloy was systematically investigated. The solution treatment time was also optimized based on the modification efficiency of Al-5Sr-8Ce. Results showed that Al-5Sr-8Ce mainly comprised α-Al, Al4Sr, and Al11Ce3 phases. With increasing addition of Al-5Sr-8Ce to 0.4 wt%, both the grain size and secondary dendrite arm space (SDAS) were significantly refined, while the eutectic Si morphology was modified from plate-like to small granular and rod-like morphologies. Grain growth inhibition caused by Ce segregation and the formation of Ce containing intermetallic compounds along the grain boundary was mainly responsible for the grain refinement. The excellent modification effect was attributed to the enhanced Sr modification and the inhibited growth of eutectic Si under the action of Ce. The multi-refinement of microstructure by Al-5Sr-8Ce improved the tensile properties of alloy, in particular a significant increase in elongation. However, the excess addition of Al-5Sr-8Ce (>0.4 wt%) increased the formation of coarse Ce containing intermetallic compounds, deteriorating the ultimate strength and elongation of the modified alloy. Based on the excellent Si modification by adding 0.4 wt% Al-5Sr-8Ce, the solution treatment time was successfully shortened to 90 min.

Published
2019

30. Influence of phase composition and microstructure on mechanical properties of hot-rolled Ti-χZr-4Al-0.005B alloys

Author

X.Y. Zhang, Mingzhen Ma, Y.K. Zhou, C.Q. Xia, C.L. Xie, Shanshan Liu, Bohan Chen, R.P. Liu, Xuwu Zhang, and Feng Zhihao

Subjects
010302 applied physics, Acicular, Materials science, Mechanical Engineering, Alloy, Metals and Alloys, Titanium alloy, 02 engineering and technology, engineering.material, 021001 nanoscience & nanotechnology, Microstructure, 01 natural sciences, law.invention, Optical microscope, Mechanics of Materials, law, Phase (matter), 0103 physical sciences, Ultimate tensile strength, Materials Chemistry, engineering, Composite material, 0210 nano-technology, Ductility
Abstract

The effects of phase composition and microstructure evolution on mechanical properties of hot-rolled Ti-χZr-4Al-0.005B alloys (abbreviated as, TχZAB with χ = 0, 10, 20, 30, and 40 wt%) were investigated by means of theoretical calculations, optical microscopy, scanning electron microscopy, and transmission electron microscopy. The as-prepared TχZAB alloys showed an excellent combination of the tensile strength and ductility features. For example, the hot-rolled T40ZAB alloy displayed the ultrahigh tensile strength of 1535 MPa at 6.06% elongation. As Zr content increased, the fracture morphologies revealed typical transitional processes from dimple to quasi-cleavage fracture surfaces. The theoretical calculations agreed well with results from X-ray diffraction, where examined alloys showed only α/α′ crystal phases. Under the same hot-rolled condition, the microstructure evolved from distorted (or broken) lamellar α phase to crisscross acicular α′ martensite phase as the Zr content increased. Finally, in search for ideal structural titanium alloys, phase composition and microstructure and relationship with mechanical properties were examined and discussed.

Published
2018

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