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Enhanced Thermoelectric and Mechanical Properties of n-type Bi2Te2.7Se0.3 Bulk Alloys by Electroless Plating with Cu

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Journal of Wuhan University of Technology(Materials Science) 2019年第4期34卷 840-844页

作者： DAI Xueting HUANG Zhongyue zu fangqiu State-owned Machinery Factory in Wuhu Wuhu 241007China School of Materials Science & Engineering Hefei University of TechnologyHefei 230009China

Bi2Te2.7Se0.3/Cu core/shell powders were prepared by electroless plating and hydrogen reduction, and then sintered into bulk by spark plasma sintering in order to improve the thermoelectric and mechanical properties of n-type Bi-Te thermoelectric material. After electroless plating, with the increasing of Cu content, Seebeck coefficient keeps increasing and power factor enhances significantly. The highest power factor increases by three times and reaches 23.8 W·cm^-1·K^-2 at room temperature in Bi2Te2.7Se0.3 with 0.22 wt%Cu sample, which means electrical transport properties of Bi2Te2.7Se0.3/Cu samples have been ***, the ZT values of Bi2Te2.7Se0.3/Cu samples can be enhanced at different temperature zone by adjusting the Cu content. Bi2Te2.7Se0.3 with 0.05 wt% Cu sample has the best thermoelectric properties in high temperature zone, and the ZT peak value increases from 0.35 to 0.85 at 623 K. When the Cu content increases to 0.15 wt%,the ZT peak value moves to the low temperature(373 K) and increases from 0.24 to 0.71. At the same time, the mechanical properties increases with the increasing of Cu content.

关键词： thermoelectric materials electroless plating thermoelectric properties mechanical properties

Functions and mechanism of modification elements in eutectic solidification of Al-Si alloys:A brief review

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China Foundry 2014年第4期11卷 287-295页

作者： zu fangqiu Li Xiaoyun Liquid/Solid Metal Processing Institute School of Materials Science and EngineeringHefei University of Technology

Being used more and more widely in engineering,AlSi alloys comprise about 80%of all kinds of aluminum alloys,which are the most widely utilized nonferrous *** most Al-Si alloys consist of multiple components,the eutectics in the structure accounts for 50%-90%of the sum volume of such ***,understanding the modification mechanism and function rules of the AlSi eutectic solidification is the technical key in controlling the structures and properties of such casting *** present paper chiefly reviews recent investigation developments and important conclusions along the lines of the functions of modification elements and their modification mechanism in the eutectic solidification of Al-Si alloys.

关键词： Al-Si alloys eutectic solidification modification silicon morphology growth kinetics

Temperature-induced liquid state change and its effects on solidification of thermoelectric alloy Bi_(0.3)Sb_(1.7)Te_3

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China Foundry 2014年第3期11卷 168-172页

作者： Zhang Wenjin Wu Zhan Yu Yuan zu fangqiu Liquid/Solid Metal Processing Institute School of Materials Science & Engineering Hefei University of Technology

The behaviors of electrical resistivity vs temperature(ρ-T) of the molten p-type thermoelectric alloy Bi0.3Sb1.7Te3(at.%) were explored in heating and cooling processes. An obvious hump appeared on the ρ-T curve from 932 ℃ to 1,020 ℃ at the heating process, while the curve became smooth in the following cooling, which suggests an irreversible temperature-induced liquid-liquid structure transition(TI-LLST) occurred in the liquid alloy. Based on this judgment, solidification experiments were carried out to find out the effects of the different liquid states. It was verified that, for the melt experiencing the presumed TI-LLST, both the nucleation and growth undercooling degrees were elevated and the solidification time was remarkably prolonged. On the other hand, the configuration of Bi0.3Sb1.7Te3 phase was refined, and its preferential orientation was weakened.

关键词： electrical resistivity liquid-liquid structure transition Bi0.3Sb1.7Te3 solidification

Effects of Electroless Plating with Cu Content on Thermoelectric and Mechanical Properties of p-type Bi0.5Sb1.5Te3 Bulk Alloys

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Journal of Wuhan University of Technology(Materials Science) 2018年第4期33卷 797-801页

作者：代雪婷黄中月 YU Yuan ZHOU Chongjian zu fangqiu School of Materials Science&Engineering Hefei University of TechnologyHefei 230009China State Key Laboratory for Mechanical Behavior of Materials Xi'an Jiaotong UniversityXi'an 710049China

Bi_（0.5）Sb_（1.5）Te_3/Cu core/shell powders were prepared by electroless plating and hydrogen reduction, and then sintered into bulk by spark plasma sintering. After electroless plating, with increasing the Cu content, the electrical conductivity keeps enhancing significantly. The highest electrical conductivity reaches 3341 S/cm at room temperature in Bi0.5Sb1.5Te3 with 0.67 wt% Cu bulk sample. Moreover, the lowest lattice thermal conductivity reaches 0.32 W/m·K at 572.2 K in Bi0.5Sb1.5Te3 with 0.67 wt% Cu bulk sample, which is caused by the scattering of the rich-copper particles with different dimensions and massive grain boundaries. According to the results, the ZT values of all Bi0.5Sb1.5Te3/Cu bulk samples have improved in a high temperature range. In Bi0.5Sb1.5Te3 with 0.15 wt% Cu bulk sample, the highest ZT value at 573.4 K is 0.81. When the Cu content increases to 0.67 wt%, the highest ZT value reaches 0.85 at 622.2 K. Meanwhile, the microhardness increases with increasing the Cu content.

关键词： Bi0.5Sb1.5Te3 electroless plating thermoelectric property mechanical property sparkplasma sintering

The effect of melt overheating on the melt structure transition and solidified structures of Sn-Bi40 alloy

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Science China(Technological Sciences) 2008年第9期51卷 1402-1408页

作者： CHEN HongSheng zu fangqiu CHEN Jie ZOU Li DING GuoHua HUANG ZhongYue Liquid/Solid Metal Processing Institute School of Materials Science and EngineeringHefei University of TechnologyHefei 230009China

Evolution of the electrical resistivity of Sn-40wt%Bi melt with time under different overheating temperatures during isothermal experiments has been studied, and the relationship between different melt state, solidification behavior and solidified structure has also been investigated. The results show that the melt structure transition revealed by the abnormal change of resistivity would take place within a certain holding time just when the holding temperature is above a certain critical, and that the higher the temperature above the critical, the shorter the "incubation period" of the melt structure transition, and the faster the transition speed. The results of solidification experiments suggest that the melt structure transition caused by different holding time at the same temperature can lead to a higher so-lidification undercooling degree, finer grain size and change of microscopic pattern. Further exploration indicates that the solidification undercooling degree can come to a head when the melt is held at the specific temperature for a given time. The functionary mechanism of the phenomena above is also discussed briefly.

关键词： Sn-Bi alloy electrical resistivity melt structure transition solidified structure

Influence of impact energy on work hardening ability of austenitic manganese steel and its mechanism

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China Foundry 2012年第3期9卷 248-251页

作者： Li Xiaoyun Wu Wei zu fangqiu Liu Lanjun Zhang Xianfeng Engineering Training Center Hefei University of Technology Hefei 230601 China School of Materials Science and Engineering Hefei University of Technology Hefei 230009 China

To further understand the hardening mechanism of austenitic manganese steel under actual working conditions, the work hardening ability was studied and the microstructures of austenitic manganese steel were observed under different impact energies. The work hardening mechanism was also analyzed. The results show that the best strain hardening effect could be received only when the impact energy reaches or exceeds the critical impact energy. The microstructural observations reveal that dislocations, stacking faults and twins increase with raising impact energy of the tested specimens. The hardening mechanism changes at different hardening degrees. It is mainly dislocation and slip hardening below the critical impact energy, but it changes to the twinning hardening mechanism when the impact energy is above the critical impact energy.

关键词： austenitic manganese steel work hardening impact energy microstructure hardening mechanism

Low-frequency Internal Friction Behaviour of Zr55Al10Ni5Cu30 Metallic Glass with Different Quenching Temperatures

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Journal of Wuhan University of Technology(Materials Science) 2017年第6期32卷 1476-1480页

作者：王知鸷 WANG Dong JIANG Peng WU Wangping LI Xiaoyan zu fangqiu SHUI Jiapeng School of Mechanical Engineering Changzhou UniversityChangzhou 213016 China School of Materials Science and Engineering Hefei University of Technology Hefei 230009 China Key Laboratory of Materials Physics Institute of Solid State Physics Chinese Academy of Science Hefei 230031 China

The correlation between the internal friction behaviour of Zr55 Al10 Ni5 Cu30 BMG samples and their quenching temperatures was investigated. It was found that, below the glass transition temperature, the activation energy decreased with increasing quenching temperature, but in the surpercooled liquid region the activation energy tended to be enhanced with a further increase in the quenching temperature. Besides, there were both anelastic and viscoelastic relaxation for the amorphous alloys. The anelastic behaviour would change into viscoelastic relaxation easily for the samples prepared at higher temperature.

关键词： internal friction quenching temperature metallic glass

Enhancing thermoelectric performance of Cu-modified Bi0.5Sb1.5Te3 by electroless plating and annealing

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Progress in Natural Science:Materials International 2018年第2期28卷 218-224页

作者： Zhongyue Huang He Zhang Kun Zheng Xueting Dai Yuan Yu Hefa Cheng fangqiu zu Zhi-Gang Chen School of Materials Science & Engineering Hefei University of Technology Institute of Microstructure and Properties of Advanced Materials Beijing University of Technology Centre for Future Materials University of Southern Queensland Materials Engineering The University of Queensland

With the capacity of energy conversion from heat to electricity directly, thermoelectric materials have been considered as an alternative solution to global energy crisis. In this work, Cu modified Bi0.5Sb1.5Te3(BST)composites are prepared by a facile electroless plating Cu method, spark plasma sintering, and annealing. The annealed 0.22 wt.%Cu/BST has an enhanced peak Figure of Merit(z T) of0.71 at 573 K with high average z T of0.65 in the wide temperature range between 300 and 573 K. Due to the significant increase of electrical conductivity and low lattice thermal conductivity, the annealed 0.22 wt.%Cu/BST shifts peak z T to high temperature, and shows 492% enhancement than that of pristine BST with z T of 0.12 at 573 K. Through detailed structural characterization of the annealed 0.22 wt.%Cu/BST, we found that Cu can dope into BST matrix and further form Cu2 Te nanoprecipitates, dislocations, and massive grain boundaries, leading to a low lattice thermal conductivity of 0.30 Wm-1 K-1 in the annealed 0.22 wt.%Cu/BST. Such enhanced peak z T in high-temperature and high average z T in the wide temperature range shows that the electroless plating Cu method and annealing can improve the thermoelectric performance of commercial BST and expand the applicability of Bi2Te3thermoelectric materials in the power generations.

关键词： Bi0.5Sb1.5Te3 Thermoelectric materials Electroless plating Annealing Average zT

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球墨铸钢第二相组织形成规律的定量研究

钢铁 1998年第1期33卷 57-59,9页

作者：祖方遒合肥工业大学

在正交试验的基础上，运用定量金相、数理统计、回归分析等方法，定量地研究了化学成分和凝固冷却条件对球墨铸钢中石墨和碳化物体积百分比的影响规律，得到了相应的数学表达关系式——回归方程。方差分析表明，试验数据及回归方程是可... 详细信息

在正交试验的基础上，运用定量金相、数理统计、回归分析等方法，定量地研究了化学成分和凝固冷却条件对球墨铸钢中石墨和碳化物体积百分比的影响规律，得到了相应的数学表达关系式——回归方程。方差分析表明，试验数据及回归方程是可靠的，从而为合理地应用球墨铸钢及生产中的质量控制提供了必要的技术依据。

关键词：球墨铸钢第二相化学成分冷速定量关系