材料期刊网

THE INFLUENCE OF Bi ON THE INTERFACIAL WETTABILITY BETWEEN SiC PARTICLES AND NiCrMo ALLOY CAST IRON

J.B. Li1) , J.P. Niu1) and X. Wang2) 1) College of Machinery , Shenyang University , Shenyang 110044 , China2) BenxiIron and Steel Company , Benxi111800 , China

金属学报(英文版)

The present paper reportsasystematicinvestigation ontheinfluenceof Bielementon thein terfacial wettability of NiCrMo alloy castiron and their related mechanism by means of thesessiledrop method . Thesurfacetension hasbeen calculated and analysised . Thestudyshows thatasmallamountof Bielementcan significantlyimprovethe wettabilitybetween SiCandNiCr Moalloycastiron. Theoptimin Bicontentis0 01 wt% .

关键词: composites , null , null , null

THE SYNTHESIS AND MAGNETOSTRICTION OF P rx Ce 1 x Fe 2 COMPOUNDS

Y.X.Li , G.Z.Xu , J.P.Qu , F.G.Liu and B.W.Wang Hebei University of Technology , Tianjin 300130 , China C.C.Tang.G.H.Wu and W.S.Zhan State Key Laboratory for Magnetism , Institute of Physics , CAS , Beijing 100080 , China C.Zhao Tianjin University , Tianjin 300072 , China S.X.Gao Hebei Normal University , Shijiazhuang 050091 , China

金属学报(英文版)

The synthesis and magnetic properties of Pr xCe 1 x Fe 2 have been investigated. The forma tion of Pr xCe 1 x Fe 2 is found to depend strongly on annealing temperature. Pure single phase compound can be synthesized at ambient pressure when x≤0 5. The main phase of the Laves structure can still be observed up to x=0 8. Magnetostriction increases with in creasing x and a largest saturation magnetostriction 200 ppm is observed for x=0.5.

关键词: magnetostriction , null , null

J(τ_0γ_0/(x_1x_2))行列式与弹塑性J积分不守恒的理论与实验证明

刘叔仪

金属学报

<正> 作为固体脆性断裂判据的J积分,其数值与其积分路径无关,这在文献中叫“守恒性”。这个守恒性已被推广到塑性断裂,这到底有否根据?本文目的是作这个问题的证明。未用原作者的方法,但由两个旋度判据得到应力应变函数行列式给出的一些否定结论,希望这对J积分应用条件的了解有所助益。1.弹塑性J积分守恒的条件 J积分

关键词:

X70管线钢J1d和K1a与V型缺口Ak关系研究

朱杰武 , 柳永宁 , 许雁 , 冯耀荣

机械工程材料 doi:10.3969/j.issn.1000-3738.2005.06.007

在不同温度下测试了X70管线钢动态断裂韧度K1d、J1d和止裂韧度K1a以及夏氏V型缺口冲击韧度Ak,对三者的关系进行了分析.结果表明:温度和加载速率都对断裂韧度产生影响;加载速率变化引起的韧-脆断裂转变具有热激活特征,在热激活分析基础上,在应力强度因子速率K=15 MPa·m1/2s-1条件下,得出断裂韧度、止裂韧度和冲击韧度三者的关系:Ak=4.84×106T-2.8K1d(或K1a).可以用小试样Ak数据计算得到K1d和K1a.

关键词: 管线钢 , 断裂韧度 , 止裂韧度 , 韧-脆断裂转变

Magnetocaloric effect and size-effect related thermal hysteresis reduction in MnAs(1-x)P(x) compounds

Physica Status Solidi a-Applications and Materials Science

In MnAs(1-x)P(x) compounds (x = 0.006 and 0.01), prepared by mechanical alloying, the thermal hysteresis is greatly reduced from about 10-30K in MnAs-based compounds, prepared by conventional melting, to 2K for x = 0.01 (or 4K for x = 0.006). Such obvious hysteretic reduction is ascribed to the grain-size effect, largely due to the preparation method of mechanical alloying. Meanwhile, a maximum value of the magnetic-entropy change Delta S(M) of 11.3 J/kgK for a field change of 2 T is obtained at 294.5K for MnAs(0.994)P(0.006). The study on the MnAs(1-x)P(x) system and also the effect of the preparation technology may be beneficial for the realization of magnetic refrigerants for application at room temperature. (C) 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

关键词: magnetocaloric effect;mechanical alloying;thermal hysteresis;gd-5(si2ge2);transition;mnas

固相反应合成Sr_(1+x)Zr_4P_(6-2x)Si_(2x)O_(24)磷酸盐粉体

姜斌 , 房明浩 , 彭鹏 , 卫礼贤 , 黄朝晖 , 刘艳改

稀有金属材料与工程

以SrCO_3、SiO_2、ZrO_2和(NH_4)H_2PO_4为实验原料,采用固相反应法制备出磷酸盐Sr_(1+x)Zr_4P_(6-2x)Si_(2x)O_(24)(x=0～0.4)粉体.XRD和SEM分析表明:在1100 ℃,4 h温度下煅烧能够合成单相Sr_(1+x)Zr_4P_(6-2x)Si_(2x)O_(24)(x=0～0.4)粉体,1100 ℃,4 h条件下制备的Sr_(1+x)Zr_4P_(6-2x)Si_(2x)O_(24)(x=0～0.4)粉体成球状,平均粒径在300～500 nm之间.在1100 ℃煅烧温度下适当延长保温时间,有利于Sr_(1+x)Zr_4P_(6-2x)Si_(2x)O_(24)(x=0～0.4)单相粉体的形成.

关键词: Sr_(1+x)Zr_4P_(6-2x)Si_(2x)O_(24) , 固相反应法 , 热膨胀系数

Magnetic properties and magnetocaloric effect of Nd(Mn(1-x)Fe(x))(2)Ge(2) compounds

Journal of Alloys and Compounds

Polycrystalline Nd(Mn(1-x)Fe(x))(2)Ge(2) (0 <= x <= 1) compounds have been prepared by arc-melting. X-ray powder diffraction analysis shows that all samples crystallize in the ThCr(2)Si(2)-type structure with the space group 14/mmm. The substitution of Fe for Mn results in decreases of the lattice constants a, c and the unit-cell volume V. Magnetic properties and magnetocaloric effect of the compounds Nd(Mn(0.9)Fe(0.1))(2)Ge(2) and Nd(Mn(0.8)Fe(0.2))(2)Ge(2) have been studied by magnetic measurements. A spin reorientation transition at about 188 K is observed for Nd(Mn(0.9)Fe(0.1))(2)Ge(2). The Nd(Mn(0.8)Fe(0.2))(2)Ge(2) compound shows more complicated magnetic behavior, which is characterized by four magnetic ordering states below room temperature. The maximum values of the magnetic entropy change are 2.35 and 1.84 J kg(-1) K(-1) for x = 0.1 and 0.2, respectively, under the applied field changing from 0 to 5T. The relative cooling powers of Nd(Mn(0.9)Fe(0.1))(2)Ge(2) and Nd(Mn(0.8)Fe(0.2))(2)Ge(2) are 145.9 and 133.8 J kg(-1) under an applied field change of 5T. (C) 2009 Elsevier B.V. All rights reserved.

关键词: Metals and alloys;Magnetocaloric;X-ray diffraction;room-temperature applications;neutron-diffraction;phase-transitions;crystal-structure;solid-solution;refrigeration;silicides;mn;0-less-than-or-equal-to-x-less-than-or-equal-to-1;mnas1-xsbx

First-principles investigations of the stability and electronic structure of ZrV2Hx (x=0.5, 1, 2, 3, 4, 6 and 7)

Acta Materialia

A calculation of the electronic structure and formation energy for ZrV2Hx (x = 0.5, 1, 2, 3, 4, 6 and 7) is performed using a plane-wave pseudo-potential method. It is found that in ZrV2Hx hydrogen forms stronger covalent bonds with vanadium than with zirconium if Zr atoms are in the neighborhood of V. A detailed analysis of how the densities of states change with the hydrogen count x in ZrV2Hx shows the changes in the bonding and anti-bonding interactions of H with V and Zr. However, the covalent anti-bonding interactions between H and V seem to be mainly responsible for the variation in the formation energy of ZrV2Hx with x. The value of projected density of states of V 3d at the Fermi level can be used as a rough comparative measure for these antibonding interactions and therefore allows us to predict the changes in stability of ZrV2Hx with x. (C) 2004 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

关键词: electronic structure;formation energy;plane-wave pseudo potential;hydrogen storage alloy;intermetallic compounds;convergence acceleration;population analysis;laves phases;total-energy;transition;hydrides;superconductivity;magnetism

H_2气氛保护热处理1J50组织结构与性能的研究

孙建春 , 盛光敏 , 陈登明 , 周安若 , 朱光俊

功能材料

1J50软磁合金的性能主要是通过H_2热处理获得的,在1130℃和H2气氛保护下对冷轧态1J50软磁合金进行了热处理.运用MATS-2010SA软磁测试仪对处理前后1J50软磁合金的磁性能进行了检测,运用金相显微镜、XRD等手段对处理前后1J50软磁合金的组织结构进行了分析.结果表明,通过H_2热处理,1J50软磁合金的矫顽力显著降低,起始磁导率和最大磁导率提高;组织结构发生明显变化,冷轧态1J50软磁合金组织为孪晶奥氏体,平均晶粒尺寸为200μm,处理过后,晶粒显著长大,平均晶粒尺寸为100μm;由于在600℃时采取了快冷,处理后1J50软磁合金中未出现大量FeNi相和FeNi_3相.

关键词: H2热处理 , 1J50 , 组织结构 , 性能

Tunable magnetocaloric effect around hydrogen liquefaction temperature in Tb(1-x)Y(x)CoC(2) compounds

Physica B-Condensed Matter

The magnetic properties and magnetocaloric effect of Tb(1-x)Y(x)CoC(2) (x = 0, 0.1, 0.2, 0.3, 0.4) compounds have been investigated systematically. All the compounds undergo second-order transitions from paramagnetic to ferromagnetic states without thermal and magnetic hysteresis. With increasing Y content from 0 to 0.4, the Curie temperatures decrease nearly linearly from 28 to 18 K. The nature of the second-order phase transitions can be confirmed by Arrott plots. For Tb(0.6)Y(0.4)CoC(2) compound, the maximum value of the magnetic entropy change -Delta S(M) at 20 K is 9.35 J kg(-1) K(-1) for an external field change of 5T (5.14 J kg(-1) K(-1) for 2T). The large reversible magnetic entropy change makes Tb(0.6)Y(04)CoC(2) compound an attractive candidate for the application at hydrogen liquefaction temperature. (C) 2010 Elsevier B.V. All rights reserved.

关键词: Curie temperature;Magnetocaloric effect;Magnetic properties;ac susceptibility