W.B. Han
,
K.F. Zhang
,
B. Wang
,
D.Z. Wu
金属学报(英文版)
The superplasticity and diffusion bonding of IN718 superalloy were studied in this article. The strain rate sensitivity index m was obtained at different temperatures and various initial strain rates using the tensile speed mutation method; m reached its maximum value 0.53 at an initial strain rate of 1×10-4s-1 at 1253K. The diffusion bonding parameters, including the bonding temperature T, pressure p, and time t, affected the mechanism of joints. When the bonded specimen with 25μm thick nickel foil interlayer was tensile at room temperature, the shear fracture of the joints with nickel foil interlayer took place at the IN718 part. Microstructure study was carried out with the bonded samples. The microstructure shows an excellent bonding at the interfaces. The optimum parameters for the diffusion bonding are: T = 1273-1323K, p = 20-30MPa, t = 45-60min.
关键词:
superplasticity
,
null
,
null
,
null
Y.D. Yu
,
K.F. Zhang
,
H.R. Zheng
,
D.M. Jiang
金属学报(英文版)
Numerical simulation and experimental studies on cavity growth were carried out during the bulging process of superplastic magnesium Alloy. A three-dimensional rigid-
viscoplastic finite element program has been developed and applied to predict the cavity radiusand volume fraction of cavity growth. The final prediction on the cavity
radius and volume fraction distribution was exhibited as colorful shade pictures. The
experimental studies wereperformed under similar conditions to the numerical one
and provided for quantitativecomparison. According to the metallography observation,
the radius and volume fraction of cavity growth was quantitative achieved by using
Profound-Iron & steel software. The numerical results were in reasonable quantitative agreement with the experiment.
关键词:
magnesium alloy
,
null
,
null
,
null
王艺慈
,
罗果萍
,
柏京波
,
郝志忠
,
邬虎林
钢铁
采用差热分析（DTA）与X射线衍射（XRD）相结合的方法，研究了高碱度烧结矿中F、K、Na对烧结固相反应开始温度与最初形成产物的影响规律，研究结果表明：烧结原料中F、K、Na的存在，促进了烧结固相反应过程中低熔点化合物硅酸钠、铁酸钠、枪晶石的形成，固相反应过程中硅酸钠自702 ℃，铁酸钠自780 ℃，枪晶石自900 ℃开始合成，从而探明了F、K、Na在烧结固相反应过程中的行为规律。
关键词:
烧结固相反应;固相反应开始温度;最初形成产物
王艺慈
,
罗果萍
,
柏京波
,
郝志忠
,
邬虎林
钢铁
采用差热分析(DTA)与X射线衍射(XRD)相结合的方法,研究了高碱度烧结矿中F、K、Na对烧结同相反应开始温度与最初形成产物的影响规律,研究结果表明:烧结原料中F、K、Na的存在,促进了烧结固相反应过程中低熔点化合物硅酸钠、铁酸钠、枪晶石的形成,固相反应过程中硅酸钠自702℃,钦酸钠自780℃,枪晶石自900℃开始合成,从而探明了F、K、Na在烧结固相反应过程中的行为规律.
关键词:
烧结固相反应
,
固相反应开始温度
,
最初形成产物
Materials Science and Engineering a-Structural Materials Properties Microstructure and Processing
The influence of sputtering on the high temperature oxidation resistance of the cast superalloy M17F has been studied. The as-sputtered microcrystalline layer has a homogeneous gamma phase structure with very fine gl ain size (20-100 nm), while the as-cast alloy is composed of gamma, gamma' and carbides. The oxidation resistance of the microcrystalline coating of K17F alloy is much better than that of the as-cast alloy, and is even superior to that of the pack aluminized alloy. At the initial oxidation stage, the oxide scale which formed on the as-cast alloy is composed of complex oxides of Cr, Ti, Ni and Al. As the: oxidation time is prolonged, the amount of alpha-Al2O3 increases and becomes the main product. However, the scale which formed on the microcrystalline coating consists only of alpha-Al2O3. Cyclic oxidation and acoustic emission examination showed that the oxide scale on the cast M17F alloy easily spalled during cooling, but the alpha-Al2O3 scale on the sputtered layer had excellent adhesion. The beneficial effects of microcrystalline structure on oxidation resistance are discussed briefly.
关键词:
K17F;sputtering;oxidation behavior
吴振雄
,
何小玲
,
周海涛
,
涂衡
,
岳银超
,
张昌龙
,
胡章贵
人工晶体学报
采用水热法,探索了 K4Gd2(CO3)3F4晶体的析晶条件,诸如生长原料及配比、生长温度、生长周期等,并成功生长了毫米级的透明单晶.对生长的晶体进行了XRD、UV-Vis-NIR、SHG等测试,结果表明,K4Gd2( CO3)3F4晶体在380～2000 nm波段的透过率超过80％,紫外吸收截止边低于200nm；其二阶非线性光学效应约为KDP的3.5倍.
关键词:
非线性光学晶体
,
K4Gd2(CO3)3F4晶体
,
水热法
Physica C-Superconductivity and Its Applications
Superconducting cuprate fluorides Nd0.7Sr1.3Cu(O,F)(4-delta) with T-c = 44 K were obtained by solid phase fluorination of the T-structure Nd0.7Sr1.3CuO4-gamma at low temperature (200-300 degrees C) using CuF2 as fluorinating reagent. The oxyfluoride has K2NiF4 structure with S.G. I4/mmm as its precursors, but the evident lattice expansions were observed. The a-axis expands from 3.7257(2) Angstrom to 3.9288(5) Angstrom and c-axis from 12.8240(3) Angstrom to 12.9630(2) Angstrom. No trace of SrF2 was detected in these fluorinated products. XRD and magnetic measurement revealed that the superconductivity in the fluorinated products originated from the oxyfluorides with reduced CuO2 plane and in the presence of the apical anion.
关键词:
hole concentration;copper;route;a=ca;tc
Physica B-Condensed Matter
The antiferromagnetic phenomena of the heterodinuclear Cu-F-Mn clusters in K2CuF4: Mn2+ and KZnF3: Cu2+- Mn2+ systems have been studied by the use of the heterodinuclear magnetic formula and the effective potential method. In our calculations two different models which are associated, respectively, with the elongated and the compressed Jahn-Teller distortion along the Cu-F-Mn direction have been taken for describing the located structures in KZnF3: Cu2+-Mn2+ system. It is demonstrated that the strong antiferromagnetic exchange interaction in KZnF3: Cu2+-Mn2+ which is about two times larger than that in K2CuF4:Mn2+ may be attributed to the Jahn-Teller compressed distortion in KZnF3:Cu2+-Mn2+. The theoretical values 2J = -143.4 and -59.9 cm(-1) are in good agreement with the experimental findings, 2J = 130 +/- 10cm(-1) in KZnF3:Cu2+ -Mn2+ and 2J = -52 +/- 2cm(-1) in K2CuF4:Mn2+ respectively. (C) 2001 Published by Elsevier Science B.V.
关键词:
exchange interaction;antiferromagnetism
