X.W.Yin
,
L.F.Cheng
,
L.T.Zhang
,
W.C.Zhou and Y.D.Xu State Key Laboratory of Solidification Processing
,
Northwestern Polytechnical University
,
Xi′an 710072
,
China
金属学报(英文版)
Strong, tough, and almost fully dense C fiber reinforced celsian matrix composites have been fabricated by impregnation of the fiber tows with the matrix slurry, winding on a drum, drying, stacking the prepreg tapes in the desired orientation, and hot pressing. The monoclinic celsian phase in the matrix was produced in situ, during hot pressing, from amphosous BAS. The unidirectional composites having ≈20 vol% of fibers exhibited graceful failure with extensive fiber pullout in three point bend tests at room temperature. Values of ultimate flexural strength and fracture toughness were 379MPa and 8 3MPa·m 1/2 , respectively.
关键词:
barium aluminosilicate
,
null
,
null
,
null
,
null
Journal of Alloys and Compounds
Thermal analysis with cooling curve has been used for investigation of microstructure evolution with composition variation during solidification process in Mg-Zn-Y-Zr alloys (denoted as ZW alloys). The obtained results reveal that two pseudobinary eutectic reactions appear one after another during solidification due to the different Zn/Y ratio (ranged front 0.35 to 3.33). In ZW62 alloy, a peritectic reaction happens before I-phase Formation through pseudobinary eutectic reaction distinguishing it from other alloys. The changes of characteristic temperature points for phase transformation are studied in detail. Microstructure observation shows dominating secondary phases in the alloys differ from one another according to various Zn/Y ratios. Divorced massive eutectic Z-phase is formed during solidification in a low Zn/Y ratio: W-phase comes out when Zn/Y ratio grows to 0.85; if the Zn/Y ratio increases further to a certain level, I-phase forms by a peritectic reaction through W-phase and the liquid. (C) 2008 Elsevier B.V. All rights reserved.
关键词:
Thermal analysis;Mg-Zn-Y-Zr alloy;Solidification pathway;Phase;constituent;mechanical-properties;system;microstructure;magnesium
Physics Letters A
The magnetic properties of the mixed ferro-ferrimagnetic compounds with (A(a)B(b)C(c))(y)D, in which A, B, C and D are four different magnetic ions and form four different sublattices, are studied by using the Ising model. And the Ising model was dealt with standard mean-field approximation. The regions of concentration in which two compensation points or one compensation point exit are given in c-a, b-c and a-b planes. The phase diagrams of the transition temperature T-c and compensation temperature T-comp are obtained. The temperature dependences of the magnetization are also investigated. Some of the result can be used to explain the experimental work of the molecule-based ferro-ferrimagnet ((NiaMnbFecII)-Mn-II-Fe-II)(1.5) [Cr-III (CN)6] - zH(2)O. (C) 2003 Elsevier B.V. All rights reserved.
关键词:
mixed ferro-ferrimagnet;Ising model;four sublattices;phase diagram;transition temperature;compensation temperature;magnetic-properties;prussian blue;alloy
Materials Science and Engineering a-Structural Materials Properties Microstructure and Processing
The microstructural evolution during solidification and subsequent solid-state transformation of AISI 304 stainless steel is studied by directional solidification and quenching methods in this paper. The phase transformation sequence in the steel directionally solidified is that the precipitation of primary ferritic dendrites, ferrite-austenite eutectic reaction, and the direct formation of austenite occur in sequence during the directional solidification of the austenitic stainless steel. At the eutectic reaction stage, plenty of columnar and cellular eutectic colonies composed of the coupled growth of lamellar ferrite and austenite take place. During the course of subsequent solid-state transformation, austenite grows into ferrite gradually, resulting in the disappearing of eutectic colonies and thinning of primary ferritic dendrites, and dendrite cores of primary ferrite are retained as the final skeletal ferrite in the final microstructure. (c) 2006 Elsevier B.V. All rights reserved.
关键词:
austenitic stainless steel;directional solidification;eutectic colony;austenitic stainless-steel;cr-ni alloys;sequence;welds
Science in China Series B-Chemistry
The equation of the state of the hydrogen bonding fluid system of A(a)D(d) type is studied by the principle of statistical mechanics. The influences of hydrogen bonds on the equation of state of the system are obtained based on the change in volume due to hydrogen bonds. Moreover, the number density fluctuations of both molecules and hydrogen bonds as well as their spatial correlation property are investigated. Furthermore, an equation describing relation between the number density correlation function of "molecules-hydrogen bonds" and that of molecules and hydrogen bonds is derived. As application, taking the van der Waals hydrogen bonding fluid as an example, we considered the effect of hydrogen bonds on its relevant statistical properties.
关键词:
hydrogen bonding fluid;equation of state;fluctuation;correlation;effect;liquid methanol;temperature;water;dependence
黄新平
,
李漠
,
吕宝军
,
赵军
,
艾兴
,
高秀生
机械工程材料
doi:10.3969/j.issn.1000-3738.2004.08.006
Y2O3-Al2O3为复合烧结助剂,以(W,Ti)C为增韧补强材料,制备了Si3N4基复合陶瓷材料.研究了Y2O3和Al2O3的配比、体积分数对Si3N4/(W,Ti)C力学性能、致密化进程和烧结性能的影响.结果表明:两者配比为2:3、总体积分数为10%时,可以获得较高的致密度和较好的烧结性能,材料力学性能最好,抗弯强度845MPa,显微硬度16.45GPa,断裂韧度7.0MPa·m1/2.
关键词:
Si3N4
,
复合陶瓷
,
烧结助剂
,
致密化
