Guoqing CHEN
,
Kaifeng ZHANG
,
Guofeng WANG
,
Y
,
ong YU
材料科学技术(英文)
Numerical simulation of hot-press sintering of nano-sized ceramic powders was introduced by the commercial finite element code MSC.MARC. The powder plastic model and the thermo-mechanical coupled quadrilateral element were developed and adopted in the simulation. The mechanical and thermal properties of the nano-sized alumina based powders were determined. In addition, the experimental research and numerical simulation of the sintering process of different initial densities were carried out. The stress state in sintering of green compacts with different initial densities was analyzed by the densification theory. The reason for the density fluctuations of as-sintered ceramic bulks was found out.
关键词:
Sintering
,
null
,
null
,
null
Zhaohua JIANG
,
Xuetong SUN
,
Yanping LI
,
Fuping WANG
,
Y
,
ong LÜ
材料科学技术(英文)
Ceramic coatings were prepared on Ti-6Al-4V alloy using ac micro-arc oxidation (MAO) in silicate-hypophosphate solution. Growth regularity and formation mechanism of ceramic coatings were discussed. It was found that during the first stage the growth rate of coatings toward the external surface was larger than that toward substrate and then the coating began to grow mainly towards Ti alloy. When the total coating thickness reaches a certain value, it would no longer increase. In addition, the variations of the composition and microstructure of ceramic coatings according to the depositing time were also investigated with X-ray diffraction (XRD) and scanning electron microscope (SEM). The amount of rutile TiO2 gradually increased, whereas the amounts of the anatase TiO2 and amorphous phases first increased and then decreased slightly.
关键词:
Titanium alloy
,
null
,
null
,
null
Min XU
,
Minxiu QUAN
,
Zhuangqi HU
,
Y
,
ong WANG
,
Liang ZUO
材料科学技术(英文)
Fe62Co8-xCrxZr6Nb4B20(x=0–4 at. pct) metallic glasses show high thermal stability with a maximum supercooled liquid region of about 84.8 K. The addition of 2 at. pct Cr causes the extension of the supercooled liquid region remarkably, leading to the enhancement of thermal stability and glass-forming ability. The crystallization of the Fe-based glassy alloys takes place through a single exothermic reaction, accompanying the precipitation of more than three kinds of crystallized phases such as α-Fe, Fe2Zr and ZrB2. The long-range atomic rearrangements required for the precipitation of the multiple crystalline phases seem to play an important role in the appearance of the large supercooled liquid region through the retardation of the crystallization reactions. The Fe-based alloys exhibit soft ferromagnetic properties. The saturation magnetization decreases with increasing Cr content while the saturated magnetostriction increases as a function of Cr content. There is no distinct change in the saturation magnetization and coercive force with annealing temperature below the crystallization temperature. The devitrification gives rise to a considerable enhancement in both δs and Hc.
关键词:
Cr addition
,
null
,
null
Yan CHEN
,
Y
,
ong GONG
材料科学技术(英文)
The magnetic abrasive machining is a method that the magnetic field (lines of magnetic force) is used to precisely machine the surface of the workpiece. When it is a magnetic workpiece, and the workpiece is magnetized and then becomes a new magnetic pole. On the contrary, when it is nonmagnetic workpiece, it can not be magnetized. In this research, the precise processing phenomenon and the condition on a shaft with steps are examined based on the experiment result mentioned above.
关键词:
Magnetic abrasives machining
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null
,
null
,
null
LUO Meiqing CHEN Nianyi Shanghai Institute of Metallurgy
,
Academia Sinica
,
Shanghai
,
ChinaYU Zhizhong Shanghai Institute of Testing Technics
,
Shanghai
,
ChianNING Yuantao ZHOU Xinming Kunming Institute of Precious Metals
,
Kunming
,
China CHEN Nianyi
,
Professor
,
Shanghai Institute of Metallurgy
,
Academia Sinica
,
Shanghai 200050
,
China
金属学报(英文版)
The electronic structure of Pd-Y-Si glass has been investigated by ESCA and quantum chem- ical calculation.It was found that the valence electrons of Y transferred to Si atoms in this metallic glass,forming polar covalent bonds.Perhaps these strong covalent bonds link Si and Y atoms to form clusters that hinder the process of crystallization.
关键词:
Pd-Y-Si glass
,
null
,
null
,
null
LI Laifeng XING Zhongshu Institute of Metal Research
,
Academia Sinica
,
Shenyang
,
China XING Zhongshu
,
professor
,
Institute of Metal Research
,
Academia Sinica
,
Shenyang 110015
,
China
金属学报(英文版)
The solubilities of Ce,Nd and Y in α-Fe at 873 to 1153 K have been deter mined by means of electron microprobe quantitative analyses.The temperature dependences of the solubilities were obtained from the experimental data.The results have been compared with those deter- mined by three other technigues,very good agreement was obtained between the results of all these techniques.
关键词:
α-Fe
,
null
,
null
,
null
,
null
翟庆洲
,
蔡建岩
,
于淼
稀有金属材料与工程
以沸石Y及以甲基三甲氧基硅烷对沸石Y进行表面改性后的Y(m)沸石作主体,用离子交换法制备Cd-Y及Cd-Y(m)样品,然后以硫代乙酰胺取代有毒的硫化氢作硫源,水热法制备Y-CdS及Y(m)-CdS主-客体纳米复合材料.利用粉末XRD、化学分析、红外光谱、固体扩散漫反射吸收光谱、发光研究对制备的样品进行了表征.化学分析表明,CdS已进入沸石Y(Ym)主体中;XRD结果表明,CdS进入沸石Y(Ym)后,制得的复合材料沸石骨架仍然存在,且保持高度有序性,不改变骨架的长程有序性;红外光谱结果表明,在所制备的Y-CdS及Y(m)-CdS样品中,有Si-O-Cd新键生成;固体扩散漫反射吸收光谱结果表明,沸石Y和Y(m)对可见光基本无吸收,Y-CdS和Y(m)-CdS吸收无明显差别;组装CdS后,Y-CdS及Y(m)-CdS产生发光现象.所制得的Y-CdS及Y(m)-CdS主-客体纳米复合材料具有作为发光材料的潜在性.
关键词:
Y沸石
,
Y改性沸石
,
甲基三甲氧基硅烷
,
纳米CdS
,
主-客体纳米复合材料
,
表征
D.Q. Wan
,
G.C. Yang
金属学报(英文版)
The microstructure formation and mechanical property involving icosahedral quasicrystal (I-phase) in the Y-rich Mg-Zn-Y alloy have been studied. The equilibrium formation of I-phase from the Y-rich Mg-Zn-Y melt is through a peritectic reaction between the Y-rich melt and the primary W-phase, which is discussed in detail. The independent nucleation and coupling growth mechanism between the W-phase and the I-phase, from the melt, are revealed, which is significant for understanding the peritectic reaction process involving icosahedral quasicrystal in the Mg-Zn-Y alloy. The mechanism of the quasicrystal phase strengthened magnesium alloys is also discussed here.
关键词:
Mg-Zn-Y
,
null
,
null
LI Bei WU Shuangxia MENG Guang'en JIANG Liping PANG Wenjie Baotou Research Institute of Rare Earth
,
Baotou
,
China Baotou Research Institute of Rare Earth
,
P.O.Box 131
,
Baotou 014010
,
China
金属学报(英文版)
With the increase of Y content in the Fe-20Cr-4AI-Y alloy,the uniform deformability of tensile specimens was found to be slightly decreased,as well as,the fracture strength and re- duction after necking remarkably dropped.This seems to be dependent upon the brittle phase containing Y.The behaviour of Y-containing phase may be improved by adjusting the metallurgical technological process.
关键词:
Fe-Cr-A1 alloy
,
null
,
null
腐蚀学报(英文)
研究了Y、Zr、Si对FeAl金属间化合物在1000~1200℃下循环氧化性能的影响,并用X射线衍射、扫描电镜及能谱分析等手段分析了氧化产物。结果表明,Y、Zr、Si的加入大大提高了FeAl金属间化合物表面氧化膜的抗剥落能力。从氧化动力学上看,Y和Zr或Y和Si的同时加入比单独加Zr效果好。
关键词:
FeAl金属间化合物
,
null
,
null