压铸Ag-Mg-Ni合金导电环的组织及性能

利用压铸成形技术制备了银镁镍合金环,并对合金的组织和性能进行了研究。结果表明,压铸成形技术制备的银镁镍合金环具有近净成形的特征,但内部存在大量孔洞;合金细晶区厚度可达300～500μm,且Mg、Ni元素分布均匀,未发现明显偏析;压铸制备的银镁镍合金环密度为10.078g/cm3、硬度(HV0.2)为44.6、电导率为43MS/m,各项性能均低于铸造-热挤压方法制备的试样。     

快速凝固Cu-Cr-Sa-Zn合金的时效强化研究

研究了时效温度、时效时间对快速凝固Cu-Cr-Sn-Zn合金微观组织、显微硬度和电导率的影响规律.结果表明,快速凝固状态下合金细晶强化作用显著,硬度(HV)和电导率分别为100和20.9 MS/m.合金快速凝固时效后的析出相Cr弥散、稠密,使合金强度和电导率得以提高,在500℃×15 min时效后,硬度(HV)为170,电导率达37.1 MS/m.     

电解液中Ce对ZAlSi12Cu2Mgl微弧氧化层的影响

在稳定的Na2SiO3电解液体系中对ZAlSi12Cu2Mgl进行微弧氧化,研究了电解液中稀土Ce的质量浓度对电解液电导率、微弧氧化过程中正/负向电流及微弧氧化层特性的影响.研究结果表明,随着Ce的质量浓度从0到0.125 g/L逐渐增加,电解液的电导率从15.15 MS/m逐渐上升到16.54 MS/m,微弧氧化过程中的电流发生明显改变;随着Ce的质量浓度的提高,微弧氧化层厚度和显微硬度先增大随后逐渐减小,在Ce质量浓度为0.025 g/L时达到最大,其氧化层厚度约为258μm;显微硬度(HV)约为620.     

内氧化法制备Al2O3弥散强化铜合金的组织和性能

用Cu2O粉作氧化剂,采用内氧化工艺制备了Al2O3弥散强化铜合金薄板.研究不同Al含量(0.14%、0.30%)和内氧化时间(3、8、12 h)下的Al2O3弥散强化铜合金薄板的电导率和硬度,并进行了显微组织分析.结果表明,内氧化时间越长,内部晶粒越粗大;其他内氧化条件相同情况下,Al含量越高,内氧化层的深度越小,内部晶粒越粗大;Al2O3弥散强化铜合金材料具有良好的电导率和较高的硬度.     

内氧化Al2O3/Cu-Cr复合材料工艺与性能的研究

通过对Al2O3/Cu-Cr复合材料内氧化粉末冶金工艺的优选,探讨了添加合金元素Cr对复合材料性能的影响.研究表明,弥散分布的Al2O3硬颗粒对基体具有明显的强化作用;加人适量的Cr所产生的沉淀强化作用进一步提高了材料的力学性能.实验表明Al2O3/Cu-Cr复合材料经过1000℃×1h固溶处理,300℃× 2h时效,硬度达到144HV,比电导率为66.7%IACS.根据实验结果,分析了弥散强化和沉淀强化共同作用下材料性能变化的趋势.     

Al2O3弥散强化Cu-25%Cr复合材料的机械变形及性能

采用真空热压烧结工艺制得Al2O3弥散强化Cu-25%Cr复合材料,分析了其显微组织与性能。经冷轧变形,研究了显微组织及性能变化,并测定了该复合材料的软化温度。结果表明：Cu-Al2O3/Cr复合材料的电导率随着轧制变形程度的增大,开始上升,然后下降。其导电率未变形时为18.3mS.m^-1,经60%变形后,导电率达到最大,为23mS.m^-1;Cu-Al2O3/Cr复合材料的硬度和抗拉强度随变形量的增加不断上升,80%变形后,硬度增加了55HV,达到150HV,抗拉强度增幅达80%,达到413MPa;并测得合金的抗软化温度约为600℃。     

时效与形变对Cu-Cr-Zr合金性能的影响

研究了时效参数和变形量对Cu 0 .3Cr 0 .0 48Zr合金组织和性能的影响。结果表明 :合金经 92 0℃× 1h固溶后 ,在 5 5 0℃时效可获得较高的电导率 ,在 5 0 0℃时效可获得较高的显微硬度。时效前加以冷变形可以加速时效初期第二相的析出 ,使合金的性能以较快的幅度上升 ,合金经 60 %变形后 5 0 0℃时效 0 .5h时 ,电导率和显微硬度分别可达 45 .96MS/m和14 2 .2HV ,而固溶后直接时效仅为 3 3 .95MS/m和 99.7HV。     

Cu-Ag-Cr合金时效特性的研究

研究了时效参数和变形量对Cu-0.1Ag-0.46Cr合金性能的影响.结果表明:合金经940℃×20min固溶后,在520℃时效1h可获得较高的电导率和硬度.时效前对合金加以冷变形可以显著提高其显微硬度,合金经60%变形后在480℃时效30min时,峰值硬度可达146.71HV,电导率可达52.9MS/m,而固溶后直接时效分别仅为123.59HV和46MS/m.而合金固溶后淬入650℃碱浴中保温20s可使合金的显微硬度和电导率均有所提高.     

电解液中Ce对ZA1Sil2Cu2Mg1微弧氧化层的影响

在稳定的Na2SiO3电解液体系中对ZAlSil2Cu2Mg1进行微弧氧化，研究了电解液中稀土Ce的质量浓度对电解液电导率、微弧氧化过程中正／负向电流及微弧氧化层特性的影响。研究结果表明，随着Ce的质量浓度从0到0．125g／L逐渐增加，电解液的电导率从15．15MS／m逐渐上升到16．54MS／m，微弧氧化过程中的电流发生明显改变；随着Ce的质量浓度的提高，微弧氧化层厚度和显微硬度先增大随后逐渐减小，在Ce质量浓度为0．025g／L时达到最大，其氧化层厚度约为258μm；显微硬度（HV）约为620。     

热压烧结制备Al2O3弥散强化Cu-25%Cr复合材料的微观组织与性能

对比研究了热压烧结和冷压-烧结工艺制得Al2O3弥散强化Cu-25%Cr复合材料的微观组织与力学、物理性能,并考察了冷变形对其性能的影响.结果表明,采用真空热压烧结工艺制得的Al2O3弥散强化Cu-25%Cr复合材料,硬度达到95 HV,电导率达18.3 MS·m-1,相对密度可达97.1%;两种方法制备的Cu-Al2O3/Cr复合材料的显微硬度随着变形量的增加而增加,最大增幅均在50%左右,分别达到142 HV和131 HV;而电导率是先增加后减小.     

Internal Oxidation of a Ag-1.3 at.% Se Alloy. Part II: Kinetics of Internal Oxidation

The kinetics of internal oxidation of a two-phase Ag-1.3 at.% Se alloy were studied at 750, 800 and 830°C in pure oxygen. The parabolic rate law was followed to a reasonable extent for the first 2 hr of oxidation. The rate of internal oxidation was much faster than expected from the classical Wagner model. Three major factors affected this: (i) the non-uniform distribution of Ag₂Se particles in the as-cast alloy caused non-uniform internal oxidation of the alloy; (ii) the formation of a liquid phase during in-situ oxidation of Ag₂Se particles accelerated the diffusional processes and lowered the activation energy of the oxidation reactions (a sort of catastrophic internal oxidation); (iii) gradual oxidation of the alloying element in the form of second-phase particles caused the extension of the single internal-oxidation front (IOF) to the internal-oxidation volume (IOV) between the inner and outer IOFs. The IOV requires a much lower oxygen quantity for its advancement than the (single) IOF thereby enabling much faster internal oxidation of two-phase alloys that oxidize in the in situ (diffusionless) mode. The kinetics are, also discussed according to the treatment which was proposed for internal oxidation of two-phase alloys by Gesmundo.⁷     

The oxidation characteristics of electrodeposited nickel composites containing silicon carbide particles at high temperature

The oxidation behaviour of electrodeposited nickel and Ni-SiC composites containing up to 13% by volume of the carbide particles in flowing oxygen at 1100°C has been studied using various kinetic and electron-optical techniques. The electrodeposited nickel oxidized more slowly than cold-rolled nickel while the introduction of up to 13 vol.% coarse SiC particles (9 μm dia.) or up to 8 vol.% fine SiC particles (3 μm dia.) to the electrodeposited nickel did not significantly change its oxidation rate. The introduction of 12 vol.% fine SiC particles did cause a significant decrease in the oxidation rate due largely to internal oxide-derived particles acting as barriers to Ni²⁺ ions diffusing through the NiO scale. The roles played in the oxidation process by doping, blocking effects in the oxide and internal oxide formation are considered and related to the oxidation rates of the composites.     

某些金属元素对Ag-Sn合金内氧化速度的影响

在0．4－0．6MPa氧压力,500和700℃下研究了某些金属元素对Ag-Sn合金内氧化速度的影响。还用SEM研究了Ag-6.5Sn-1.1Bi-0.6Cu合金内氧化层的微观结构。结果表明,氧化层厚度与时间成抛物线关系。添加金属元素对Ag-Sn合金的内氧化速度有明显的影响,易氧化的金属元素能加速Ag-Sn合金内氧化。氧化物以微细颗粒分布在银基体中,发现在晶界处有部分氧化物聚集,并且有2－5μm以某种氧化物为主的细小颗粒。     

Internal Oxidation Thermodynamics and Isothermal Oxidation Behavior of AgSnO2 Electrical Contact Materials

研究了Ag-Sn合金内氧化热力学与恒温氧化行为。热力学计算结果表明,Ag-Sn合金内氧化在热力学上是可行的,并绘制了合金氧化热力学区位图。经氧化实验获得Ag-Sn合金恒温氧化行为曲线。Ag-Sn合金快速氧化的温度区间为550℃至800℃。随内氧化温度的升高,合金的氧化更为彻底并逐步趋于平稳。实验所得AgSnO2材料中,SnO2颗粒弥散分布于Ag基体中。在内氧化过程中,氧的扩散使合金内部发生氧化,并生成呈网状排布的氧化物。     

Internal Oxidation of a Ag-l.3 at.% Se Alloy. Part I: Composition and Appearance of Oxidation Products

The internal oxidation of a two-phase Ag-1.3 at.% Se alloy in pure oxygen was studied at 750, 800 and 830°C. The alloy is composed of a dilute solid solution of selenium in silver) and Ag₂Se intermetallic particles. The internal oxidation of this alloy proceeds through gradual in-situ oxidation of the Ag₂Se particles as well as through diffusive internal oxidation of selenium from solid solution. Gradual in-situ internal oxidation of Ag₂Se particles reflects itself in the appearance of two internal-oxidation fronts, inner and outer, marking the beginning and end of the in-situ oxidation of Ag₂Se particles. The oxide phase formed during in-situ oxidation is the molten double oxide, Ag₂SeO₃. A theoretical treatment of the phase relationships in a hypothetical Ag–Ag₂Se–Ag₂SeO₃ ternary phase diagram is presented to assist the explanation of the mechanism of in-situ oxidation. The kinetics of oxidation are presented in Part II.     

INTERNAL OXIDATION KINETICS & DIFFUSION MECHANISM OF OXYGEN IN Cu-Al SINTERED ALLOY

In this paper, internal oxidation kinetics and the diffusion mechanism of oxygen in sintered Cu-Al alloy have been studied by means of scanning electron microscopy,transmission electron microscopy and heat-weighting scales. The results show that the kinetic curves obey the parabolic law in the initial stage and are linear in the late stage.The oxygen atoms are mainly transported in the from of grain boundary diffusion and volume diffusion in the process of internal oxidation. The plastic deformation of Cu matrix around oxide particles increases the probability of [O] atoms moving in accordance with dislocation diffusion mechanism. Meanwhile, the activation energy and diffusion coefficient in the process of internal oxidation are evaluated by means of kinetic method so as to obtain the velocity equations of reacting interface moving in different stage.     

花状自组装FePt纳米颗粒的制备

选用硼氢化钠(NaBH4)作为还原剂,聚乙二醇(PEG2000)作为表面活性剂,利用简单的湿化学还原工艺,在室温下制备花状自组装的FePt纳米颗粒。XRD和TEM表征显示:所制备的FePt纳米颗粒是化学无序的面心立方(fcc)结构。颗粒形貌主要由平均粒径分别为19.2和4.9nm的梭形和球形颗粒组成。这些梭形的"花瓣"和球形的"花蕊"自组装形成大小不等的花状结构。推测认为,纳米颗粒的花状自组装主要是表面活性剂集合的结果。VSM显示所制备FePt纳米颗粒的磁性能室温下为超顺磁性,饱和磁化强度Ms约为10.9(A·m2)/kg,相同条件下PVP作为表面活性剂时Ms约为0.6(A·m2)/kg,两者比较,选用PEG作为表面活性剂,Ms大约增大18倍。     

The Effect of Supersaturation on the Internal Oxidation of Binary Alloys

According to the theory of Bohm and Kahlweit ofthe internal oxidation of binary A-B alloys, theparabolic rate constant for the formation of reasonablystable internal BO oxides as well as theconcentrations of O and B at the oxidation front arecontrolled only by the degree of supersaturationnecessary for the nucleation of new oxide particles. Theeffects of this factor on the previous parameters arecalculated for various values of the solubility product ofthe oxide and of the diffusion coefficients of O and B.Moreover, an alternative procedure for the calculationof the critical degree of supersaturation behind the precipitation front required for oxideprecipitation, which is a function of the concentrationof the reactants at the internal oxidation front, isproposed. A simple modification of Wagner's theory of internal oxidation is also presented, andits results are compared with those of the treatment byBohm and Kahlweit. Finally, the limitations of the twomethods are examined.     

Internal Oxidation of an Ag–1.3 at.% Te Alloy

The internal oxidation of Ag–1.3 at.% Te was studied at 750, 800, and 830°C in pure oxygen (1 atm). The internal oxidation under such high oxygen pressure resulted in formation of two different types of oxide particles and two different fronts of internal oxidation in the internal oxidation zone. The coarser Ag₂TeO₃ particles were formed through the in situ internal oxidation of Ag₂Te particles and the tiny oxide precipitates (most probably also Ag₂TeO₃) were formed through internal oxidation of tellurium from solid solution. Considering the mechanism of internal oxidation, both diffusionless and diffusive modes were found to be present simultaneously in the oxidation of Ag–1.3 at.% Te alloy. These results were examined with regard to the solubility of tellurium in silver, which was found to be 0.1 at.% Te at 750°C and 0.26 at.% Te at 830°C, as well as the presence and dissolution of Ag₂Te particles.     

表面氧化物在7050铝合金搅拌摩擦焊焊接接头中的分布

利用阳极氧化方法在待焊材料表面生成一层厚12.7μm的Al2O3膜,采用搅拌摩擦焊进行焊接,用扫描电镜检查接头横截面氧化物分布,确定表面氧化物对接头抗拉强度的影响.结果发现:焊缝中心上表面到下表面,氧化物颗粒数量急剧降低,颗粒尺寸减小;热影响区和热-机影响区交界区氧化物颗粒数量高于焊核区,尺寸较大,约3.3μm,颗粒含...