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Influence of Carbon Content and Solidification Condition on Incipient Melting of DS Superalloy MAR-M200+2Hf

ZHENG Yunrong , WANG Luobao , LI Chenggong Institute of Aeronautical Naterials , Beijing , China. To whom correspondence should be addressed.

材料科学技术(英文)

Hf lowers the incipient melting temperature of superalloy. As carbon content in Hf-bearing alloy decreases, the incipient melting temperature drops furthey. PD ingots have stronger tendency to incipient melting than HRS ones. Even though in PD ingot, the sensitivities at both ends of the ingot are quite different. The melting of Ni_5Hf phase may be considered as one of the main factors affecting incipient melting. The more Ni_5Hf the alloy contains, the more serious the incipient melting becomes. The results of differential thermal analysis (DTA) have proved that the peak of 1135-1160℃ corresponds to the melting range or Ni_5Hf. By means of a pretreatment at 1150℃, 8h, Ni_5Hf phase can be eliminated in two ways: the reaction Ni_5Hf+γ(C)→MC_(2)+γ and solid solution, and therefore the final solid solution treatment can be carried out at 1260℃. This brings about a high homogenized structure and further increases the stress rupture properties of the alloy at 1040℃, 140 MPa.

关键词: DS superalloy , null , null , null , null , null

Image analysis of periodic rain accelerated corrosion of aeronautical aluminium alloys

Materials Science and Engineering a-Structural Materials Properties Microstructure and Processing

Periodic rain tests have been carried out for simulating atmospheric corrosion of aeronautical aluminium alloys. A digital image preprocessing and analysis method based on wavelet transformation was used to study the corrosion morphology of aluminium alloys samples, through which an image feature parameter 8 was extracted and discussed. The influences of orthogonal experiment parameters on acceleration were analyzed according to image feature parameter 6 with analysis of variance (ANOVA) method, and the optimal parameters for accelerated corrosion test were also obtained. The result was shown to be consistent with that from weight loss method. (c) 2007 Elsevier B.V. All rights reserved.

关键词: aeronautical aluminium alloys;accelerated corrosion;linage analysis;simulated environment;atmospheric corrosion;electrochemical impedance;pitting corrosion;exposure;steel;zinc

STRUCTURE FEATURES IN BINARY-LIQUID LI-TL ALLOYS

Journal of Chemical Physics

With the help of potential mapping techniques, molecular dynamics simulations have been performed to study the local structure features in binary liquid Li-Tl alloys. The generalized nonlocal model pseudopotentials have been chosen as the bases for our calculations. Both the bond orientational order and pair analysis approach have been adopted as the basic structural functions to examine the structure features in binary liquid Li-Tl alloys. In addition, bonded pairs with various symmetries, icosahedra, defective icosahedra, Frank-Kasper polyhedra, etc., formed in the Li-Tl alloys are examined in detail, and the relationship between the structure features and composition has been established. The results show that the distribution of attractive parts of the potentials play an important role in characterizing the Liquid structure. Finally, the results are discussed in detail. (C) 1995 American Institute of Physics.

关键词: variational thermodynamic calculations;bond-orientational order;rapidly quenched metals;molecular-dynamics;sd metals;glasses;crystallization;transitions;solids

ON SPINODAL BOUNDARIES OF Al-Li ALLOYS

WEI Yinghui , WANG Xiaotian (School of Materials Scince and Engineering , Xi'an Jiaotong University , Xi'an 710049 , China Manuscript received 10 Mareh , 1994)

金属学报(英文版)

The spinodal decomposition can occur in Al-Li alloys containing 5.8-14.2 at.% Li at room temperature. The modutated structure wavelength is approximately 3.1 nm for com mercial Al-LI alloys. The limit composition of the miscibility gap is 3.66 -16.06 at.%Li at 298 K. The highest temperature of the miscibility gap is 377 K.

关键词: : Al-Li alloy , null , null

大爆炸核合成相关的8Li(d, p)9Li反应截面测量

李志宏 , 柳卫平 , 白希祥 , 郭冰 , 连钢 , 颜胜权 , 王宝祥 , 陆昀 , 曾晟 , 苏俊

原子核物理评论 doi:10.3969/j.issn.1007-4627.2005.01.006

利用8Li次级束测量了质心系能量7.8 MeV 2H(8Li, 9Li)1H反应的角分布, 导出了8Li(d, p)9Li反应的天体物理S因子及9Li→8Li+n虚衰变的渐近归一化系数.

关键词: 8Li(d,p)9Li反应 , 角分布 , 天体物理S因子 , 渐近归一化系数

CRYSTAL STRUCTURE OF γ-Li_xFe_2O_3 WITH ELECTROCHEMICAL INSERTION OF Li

HUANG Jianshun CHEN Junming Shanghai Institute of Metallurgy , Academia Sinica , Shanghai , China Research Associate , Shanghai Institute of Metallurgy , Academia Sinica , Shanghai 200050 , China

金属学报(英文版)

Crystal structure of γ-Li_xFe_2O_3,inserted Li electrochemically,was studied by Moss- bauer spectroscopy together with X-ray diffraction,XPS and electrochemical method,On the insertion of Li at low current density,the crystal structure is keeping original spinel; while at higher current density or by thermal activation,owing to violent movement of Li~+ ions,part of crystal structure transforms into rock type similar to face-centered cubic structure of ferrous oxide.The transition channels during insertion of Li~+ ions and limitation of Li~+ ions inserted were discussed.

关键词: null , null , null

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