热处理对ZCuSn3Zn8Pb6Ni1FeCo合金组织性能的影响

利用真空离心铸造方法制备的ZCuSn3Zn8Pb6Ni1FeCo合金试样,经850～900℃下保温1.0～3.0h后水淬固溶处理,随后在时效处理温度450、500、550和600℃下分别保温4h,用XRD、SEM、HREM分析研究该合金时效工艺对组织性能的影响。结果表明:ZCuSn3Zn8Pb6Ni1FeCo合金以α-{Cu,Sn}为基体,存在有硬脆δ-Cu10Sn3相,强化析出相主要有α-Fe、γ-Fe、CoCu2Sn、Fe3Co7、Fe4Zn9等,铅以单质形式析出;与铸态相比合金经过固溶处理后抗拉强度提高33.3%,伸长率提高55.1%;合金经500℃时效4h处理,抗拉强度与常规固溶处理相比提高了8.3%,伸长率却下降了55.1%;ZCuSn3Zn8Pb6Ni1FeCo合金中强化析出相Fe4Zn9和基体Cu形成半共格关系;α-Fe和基体Cu形成完全共格关系;ZCuSn3Zn8Pb6Ni1FeCo合金经固溶处理后,共格强化效果与Orwan公式计算结果非常接近,而固溶强化、空位强化和细晶强化的贡献甚微。     

第二相粒子尺度对ZCu10Sn2ZnFe合金力学性能的影响

采用真空熔炼-离心铸造工艺制备新型ZCu10Sn2ZnFe合金;通过透射电镜,研究了Fe含量对ZCu10Sn2ZnFe合金中的Fe相粒度分布和形貌的影响,证实了基体中纳米Fe颗粒的存在,通过小角散射实验确定了Fe添加量分别为1％、1.5％和2％时合金基体中纳米铁颗粒的平均半径和体积分数,并根据奥洛万机制和共格界面原理,分析了粒子尺度对材料力学性能的影响.     

Cu-2.1Fe合金中共格γ-Fe粒子的粗化规律与强化效果

采用TEM,SEM,硬度及电导率测试等手段,研究了Cu-2.1Fe合金在不同温度长期时效后析出相形貌和合金性能的变化.结果表明,500℃为合金最佳时效温度,峰时效硬度平台期较长.合金峰时效时γ-Fe粒子平均直径约12 nm,且与基体完全共格.g-Fe粒子长大后会渐渐失去共格效应且方形化,粗化规律符合Lifshitz-Slyozov-Wagner(LSW)规律,粗化激活能为222 kJ/mol.Fe粒子的时效强化效果不显著,最大强度增量约100 MPa.Cu-2.1Fe合金欠时效时遵循的强化机制为共格强化机制,合金过时效后强化机制为Orowan强化机制,理论预测与实验结果符合良好.     

Cu-Ni-Si合金时效析出相的长大机制研究

通过测量导电率研究了Cu-3．2Ni-0．75Si-0．30Zn合金在时效过程中的调幅分解行为。结果表明,合金在450℃时效时按照调幅分解机制经历了三个序列:溶质富集区→半共格Ni2Si相→非共格Ni2Si相。即随时效时间的延长,溶质原子富集区出现有序化,形成与基体半共格的强化相(Ni2Si)。继续时效,强化相不断析出与长大, 半共格关系被破坏,最终在表面张力的作用下逐渐球化,导电率和显微硬度上升趋势随之减弱。     

单相纳米晶Nd12.3Fe79.2Nb2.5B6合金的交换耦合作用与显微组织

采用熔体快淬及晶化退火工艺制备了含铌单相纳米晶Nd12.3Fe79.2Nb2.5B6合金,研究添加Nb对单相Nd2Fe14B纳米晶合金的磁性能、交换耦合和微观结构的影响规律.结果表明:Nb的添加提高了合金的非晶热稳定性,使得合金最佳晶化温度升高;合金晶化退火后,Nb可使晶粒尺寸分布均匀,并得到单一Nd2Fe14B相;晶粒边界比较完整,存在共格、半共格或大角度晶界,但没有观察到晶界相.上述结构可有效提高合金的磁性能,增强交换耦合作用.通过对Nd12.3Fe79.2Nb2.5B6合金磁性能分析可知:650 ℃晶化退火10 min后的合金性能最佳,交换耦合作用最强.     

Cu-Ni-Si合金时效析出相的长大机制研究

通过测量导电率研究了Cu-3．2Ni-0．75Si-0．30Zn合金在时效过程中的调幅分解行为。结果表明，合金在450℃时效时按照调幅分解机制经历了三个序列：溶质富集区→半共格Ni：Si相→非共格Ni：Si相。即随时效时间的延长，溶质原子富集区出现有序化，形成与基体半共格的强化相（Ni：Si）。继续时效，强化相不断析出与长大，半共格关系被破坏。最终在表面张力的作用下逐渐球化，导电率和显微硬度上升趋势随之减弱。     

Zr─4合金氧化膜中Zr(Fe,Cr)2第二相粒子的HREM观察

应用透射电子显微镜(TEM)和高分辨电子显微镜(HREM)研究了在400℃,10.3MPa过热蒸汽中形成Zr-4合金氧化膜中的Zr(Fe,Cr)2第二相粒子。结果表明,嵌在合金氧化膜中的Zr(Fe,Cr)2粒子表面生成面心立方结构的Zr6(Fe,Cr)3O,它与Zr(Fe,Cr)2存在共格关系。在上述氧化物之上为氧化物立方ZrO2和金属相α-Fe(Cr)的混合物。     

Fe含量对ZCuSn10Zn2FeCo合金组织性能的影响

采用普通砂型铸造的方式研究了不同Fe含量对ZCuSn10Zn2FeCo合金组织和性能的影响.利用金相显微镜、SEM、TEM等测试手段研究了Fe含量对ZCuSn10Zn2FeCo合金的组织性能影响.结果表明:ZCuSn10Zn2FeCo合金以Cu(Sn,Zn)固溶体为基体,强化相主要为富铁相.当铁含量为2％时,ZCuSn10Zn2FeCo合金强化效果明显,抗拉强度和伸长率分别为350 MPa和13.5％,合金晶粒大小在40 ～100 μm,基体中存在着数量众多、弥散分布的纳米强化相.随着Fe含量的增加,黑色析出相发生了粗化现象,合金试样的抗拉强度则下降为320 MPa左右,伸长率下降到了8％.     

新型耐高压铸造锡青铜的研制

以ZCuSn3Zn8Pb6Ni1合金为基础,通过添加Fe和Co,开发了耐高压铸造ZCuSn3Zn8Pb6Ni1FeCo合金,研究了Fe和Co对合金组织和性能的影响.结果表明,ZCuSn3Zn8Pb6Ni1FeCo合金显微组织与ZCuSn3Zn8Pb6Ni1的相同之处在于均以α-{ Cu,Sn,Zn }为基体,存在硬脆相δ- Cu10Sn3,Pb以单质形式析出;ZCuSn3Zn8Pb6Ni1FeCo合金中还存在α-Fe和γ-Fe析出相,以及CoCu2Sn 、Fe3Co7、Fe4Zn9等硬质相,这些硬质相和基体之间为共格或半共格关系;ZCuSn3Zn8Pb6Ni1合金铸造组织为典型的枝晶组织,晶粒平均直径约3 mm,抗拉强度为180～230 MPa,而ZCuSn3Zn8Pb6Ni1FeCo合金为等轴晶组织,晶粒平均直径为20～60 μm,抗拉强度为400～450 MPa,伸长率在20%以上;ZCuSn3Zn8Pb6Ni1FeCo合金消除了明显存在于ZCuSn3Zn8Pb6Ni1合金中的Sn的宏观偏析.     

离心对ZCuSn3Zn8Pb6Ni1FeCo合金析出相行为的影响

采用真空熔炼-离心铸造工艺制备出ZCuSn3Zn8Pb6Ni1FeCo合金试样。利用专用图像分析软件确定试样的晶粒度,并通过光学显微镜、TEM等分析手段,研究了离心对析出相行为的影响。结果表明:与常规铸造工艺相比,离心铸造使得平均晶粒直径由88～125μm降低到44～62μm,晶粒细化明显;析出相分布呈双峰分布,与非离心相比,离心条件下粗大析出相明显细化,细小析出相变化不大,且与基体间保持共格或半共格关系;离心压力对金属组织性能的影响主要原因是离心压力降低了临界晶核形核功,提高了扩散激活能,使晶粒细化。     

胫骨生物陶瓷复合材料的微结构增韧机理

扫描电镜观察显示胫骨是一种由羟基磷灰石和胶原蛋白组成的自然生物陶瓷复合材料.羟基磷灰石具有层状的微结构并且平行于骨的表面排列.观察也显示这些羟基磷灰石层又是由许多羟基磷灰石片所组成,这些羟基磷灰石片具有长而薄的形状,也以平行的方式整齐排列.基于在胫骨中观察到的羟基磷灰石片的微结构特征,通过微结构模型分析及实验,研究了羟基磷灰石片平行排列微结构的最大拔出能.结果表明,羟基磷灰石片长而薄的形状以及平行排列方式增加了其最大拔出能,进而提高了骨的断裂韧性.     

Prospects of the Use of Synergetic Approach to Solution of Problems of the Science of Nanomaterials

A synergetic approach to solution of problems of self-controlled synthesis of nanostructures and creation of self-organizing nanotechnologies is considered in connection with the superproblem of creation of materials with functional properties resembling those of biosystems. __________ Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 7, pp. 55 – 61, July, 2005.     

Kinetics of the oxidation of metals — Influence of self-diffusion of metal

The importance of the self-diffusion of a metal during its oxidation by a gas is treated for the cases of nonstoichiometric oxides having either interstitial cation or cation vacancies. We have established a general relationship for the reaction rate when a mixed diffusion process occurs. From this relationship, we have shown that the pressure dependence can be different, according to whether the rate-determining process is the self-diffusion through the metal or through the product.     

Features of formation of the structure in production of blanks of disks of heat-resistant nickel alloys

Conclusions To provide a high level of mechanical properties in wrought blanks of cast ÉP741NP and ÉP962 alloys it is necessary to form controlled structures. A necklace-type structure formed in homogenizing isostatic treatment, subsequent thermomechanical working including alternation of the operations of deformation in the (+)-area and recrystallization anneals, and final heat treatment is preferable. The temperature conditions of all stages of thermomechanical working are strictly controlled, especially the final operation of deformation and heating for hardening. To eliminate hardening cracks and distortions it is necessary to use molten salts at t=600°C as quenchants. The use of multiple production operations makes it possible to significantly reduce the structural inhomogeneity related to inhertance of the original dendritic structure. However, the structure of the final semifinished product is nevertheless characterized by a difference in occurrence of the processes of polygonization and recrystallization between the former dendritic cells and the interdendritic spaces in deformation and heat treatment.To obtain structurally homogeneous blanks for gas turbine engine parts it is necessary to use basically new methods of remelting such as vacuum double electrode remelting and electron beam remelting with an intermediate vessel.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 12, pp. 25–29, December, 1991.     

Ab-initio calculation of enthalpies of formation of intermetallic compounds and enthalpies of mixing of solid solutions

A large number of ab-initio calculations of energies of formation of intermetallic compounds have been performed in the last 15 years. The currently used methods are listed. The paper presents a review of the aluminium based compounds which have been studied. Comparisons of calculated and experimental enthalpies of formation are provided for aluminim-3d and-4d transition metal alloys at equiatomic composition. The modelling of the enthalpies of mixing of solid solutions based on a given lattice is described.     

试论洋务派教师聘任的思想

洋务派在洋务学堂的办学活动中,为了解决西学专业学科的教学困难,采用了聘请外籍教师的应急措施.他们以真才实学,合同制管理作为主导思想,并认为这种解决师资的途径只是权宜之计,并非久远.从客观上看,洋务派的教师聘任思想有深刻的历史影响.