Effects of precipitates on fatigue crack growth rate of AA 7055 aluminum alloy

The effects of precipitates on the fatigue crack growth rate of AA 7055 Al alloy subjected to different ageing treatments were investigated using transmission electron microscope and fatigue crack growth testing.The results show that the T77 treated samples exhibit the lowest crack growth rate,while the crack growth rate of over-aged samples is the highest.In terms of the model based on the reversibility of dislocation motion within the plastic zone close to the crack tip,the improved crack growth resistance is attributed to many precipitates that are coherent with Al matrix in the under-aged and T77 treated samples.When the precipitate is coherent with the Al matrix,the larger the precipitate is,the slower the fatigue crack grows.The effects of grain boundary precipitates and precipitate free zone on the fatigue crack growth resistance are less significant than those of precipitates within grains of the alloy.     

Al-Sc-Zr合金中析出相的形成及再结晶抑阻(英文)

通过冷硬铸造法制备Al-x%Sc-0.11%Zr合金(x=0,0.02,0.05,0.08,0.11,0.15),研究合金在475°C保温12h热处理条件下不同钪含量对Al3(Sc,Zr)析出的影响。研究发现,Al3(Sc,Zr)析出相的形核、析出和分布与钪含量密切相关。透射电子显微镜研究表明,随着钪含量的增加,析出相的平均半径减小,密度增大,分布变得越来越均匀。将90%冷轧样品在200-600°C的温度区间等温退火0.5h,再进行抗再结晶能力的研究。结果表明,未添加钪的合金的再结晶温度为250°C,而添加0.15%钪后形成的Al3(Sc,Zr)析出相使得再结晶温度升高到约600°C。     

Effect of oxygen precipitates in solar grade silicon on minority carrier lifetime and efficiency of solar cells

The effect of oxygen precipitates on minority carrier lifetime and performance of solar cell was studied by means of Fourier Transform Infrared Spectroscopy (FTIR), quasi-steady state photoconductance (QSSPCD), optical microscope, spectrumresponse and solar cell efficiency test. The minority carrier lifetime and performance of solar cell reduced depend on oxygen precipitates. A few of oxygen precipitates have formed after single-step annealing; and they do not impact the efficiency dramatically. Pre-annealing at 650 ℃ for 4 h enhances the oxygen precipitation when it is subjected to middle temperature annealing. The solar cells performance decayed sharply. Especially annealing at 950 ℃ for 3 h, the V os and I sc of cells decrease 12% and 25% respectively. Few oxygen precipitates have formed in silicon after high temperature annealing at about 1050 ℃ whether pre-annealing is used or not, and the performance of cells is notbe affected.     

低氮低钒D36船板钢中析出相的特征及沉淀强化作用

通过透射电镜观察了低氮低钒D36船板钢的析出相特征,并讨论了其沉淀强化作用。结果表明:实验用钢的组织均为铁素体-珠光体组织,珠光体中未见析出相,仅在铁素体中观察到析出相。VCx析出相为矩形片状形貌,在铁素体基体上均匀弥散沉淀,析出相以{100}α-Fe为惯习面,与基体存在Baker-Nutting取向关系;少量球状V6C5析出相(单斜结构)与铁素体基体存在一定取向关系,可能是共格VCx相通过碳原子重新分布转变而成。低氮低钒钢中加入0.05%V,沉淀强化值约为63 MPa,加入微量铌后在铁素体内形成一定密度的位错能有效发挥钒的沉淀强化作用。     

对称过渡阶段时间对双丝MIG焊的影响

根据国内外对双丝电流波形控制的研究现状和两丝之间电磁力大小的关系,提出一种双丝MIG焊对称过渡波形控制工艺方法.针对有无对称过渡阶段和双丝过渡阶段时间Ts对焊接效果的影响进行了试验研究.结果表明:增加对称过渡阶段有助于提高焊接过程稳定性.在当前试验条件下,双丝过渡阶段时间Ts不宜低于1 ms,否则无法体现对称过渡控制的优势;不宜高于峰值时间,否则会影响焊缝质量,降低焊接速度;过渡时间为2～3 ms时,能够获得稳定的波形和良好的焊缝.试验结果为对称过渡波形控制方法提供了基本的工艺数据,为双丝电流波形控制研究提供了新的方法.     

电子辐照对CuZnAl形状记忆合金相变温度的影响

用能量1.7MeV不同注量的电子辐照CuZnAl形状记忆合金样品, 辐照在母相进行. DSC实验结果表明, 辐照前后样品的相变温度As从339K升高到347K, Ms从330K升高到340K, As-Ms从4K升高到7K. XRD分析结果表明辐照导致两组成对晶面间距差(Δd)增大, 证明辐照促进了有序化. 相变温度的变化是由于电子辐照产生的点缺陷造成了马氏体相点阵畸变和有序度的变化, 从而产生马氏体稳定化.     

常化冷却工艺对低温取向硅钢组织及析出相的影响（英文）

利用OM、TEM与EDS技术,对Fe-3.2%Si低温取向硅钢热轧板进行不同常化冷却工艺处理后的显微组织、析出相及最终产品的磁性能进行分析,并与热轧板的组织和析出相进行对比。结果表明,常化板较热轧板的表层组织均匀,基体中再结晶比例增加,带状组织变窄;常化板中析出物的数量明显比热轧板的多,析出物主要有AlN、MnS及复合析出的(Cu,Mn)S等。在常化温度1120℃、保温3 min的条件下,采用二段式冷却较空冷、淬沸水、淬常温水的冷却工艺,常化板表层显微组织更均匀,沿板厚方向的显微组织的不均匀性显著,取向硅钢的磁性能最高;常化后采用二段式冷却工艺析出的细小析出物数量最多,且弥散分布在基体中,抑制剂的抑制效果最好,对成品获得高磁性最有利。     

Jarosite-type precipitates mediated by YN22, Sulfobacillus thermosulfidooxidans, and their influences on strain

To have a better understanding on the properties of the jarosite-type precipitate synthesized by Sulfobacillus thermosulfidooxidans, the evolution of the S. thermosulfidooxidans-mediated precipitation and the influence of the precipitate on this species, a newly isolated strain （YN22） ofS. thermosulfidooxidans was cultured in a medium containing Fe^2＋ as energy source under optimal conditions （pH 1.5, 53 ℃, 0.2 g/L yeast extract, 30 g/L Fe2SO4·7H2O and 170 r/min）, added with or without glass beads. Remarkable differences were found in the oxidation rate of Fe^2＋, the precipitate yield ofjarosite-type compounds and the population density between the two groups of cultures. The group with glass beads has a 6 h faster Fe^2＋ oxidation, 6 h earlier precipitation, 78% higher precipitate yield and much lower population density than those without glass beads. XRD, EDS, FTIR and SEM analysis reveals that the precipitates originated from both groups are a mixture of potassium jarosite and ammoniojarosite, with morphological features similar to the latter. The results of the test referring to influence of the precipitates on YN22 show that the precipitate from the group without glass beads has no apparent influence on Fe^2＋ oxidation rate of YN22 and only a limited influence on growth of the strain, whereas that from the group with glass beads remarkably inhibits the growth and Fe^2＋ oxidation ability of YN22 when a precipitate content over 4 g/L is used.     

双相不锈钢表层沉淀相的晶体学特征

双相不锈钢00Cr25Ni7Mo3表层析出的奥氏体相具有可重复的多种形貌和晶体学特征,与块体材料内部的沉淀现象有显著差异.为探索非均匀约束条件下的相变晶体学规律,应用电子背散射衍射(EBSD)技术对表层沉淀相中主要的针状奥氏体的晶体学特征进行统计表征.统计结果表明,沉淀相倾向于沿表面生长.以在预抛光表面作为不变线方向的约束条件,计算了所有可能出现的不变线.对比实验观察发现,多数表层沉淀相的长轴方向趋向表面内的某一不变线.各不变线之间的晶体学非等价性是表层针状沉淀相取向多样性的成因.     

Crystallography of Mg2Sn precipitates in Mg-Sn-Mn-Si alloy

The microstructures of a Mg-Sn based alloy with trace additions of Mn and Si after various ageing heat-treatments were investigated. The alloy was found to contain mostly Mg2Sn（fl） precipitates. The morphology and orientation relationships（OR） of Mg2Sn precipitates were analyzed by using TEM. The Mg2Sn precipitates mainly exhibit three shapes： lath, polygon and plate. Four ORs between Mg2Sn precipitates and Mg（a） matrix are repeatedly detected, and two of them have never been reported before. Most of the lath-shaped fl precipitates exhibit two OR. One is （0001）α/（110）β, [11^- 20]α//[001]β （OR-I）, with the long axis along [11^-20]α//[001]β; and the other is （0001）α/（110）β, [1^-100]α//[31^1]β （OR-2, a new OR）, with the long axis along [1^100]α//[31^-1]β. The polygonal β exhibits （0001）α/（111）β, [2^110]β//[^-110]β（OR-3）, with several pairs of facets. The plate-shaped fl exhibits （0001）α/（111）β, [2^-11 0]α deviates by about 9 from [^- 110]β （OR-4, a new OR）.     

Comparison of neutron irradiation effects on the electrical performances of SiGe HBT and SiBJT

The change of electrical performances of silicon-germanium (SiGe) heterojunction bipolar transistor (HBT) and Si bipolar junction transistor (BJT) was studied as a function of reactor fast neutron radiation fluence. After neutron irradiation, the collector current Ic and the current gain β decrease, and the base current Ib increases generally for SiGe HBT. The higher the neutron irradiation fluence is, the larger Ib increases. For conventional Si BJT, Ic and Ib increase as well as β decreases much larger than SiGe HBT at the same fluence. It is shown that SiGe HBT has a larger anti-radiation threshold and better anti-radiation performance than Si BJT. The mechanism of performance changes induced by irradiation was preliminarily discussed.     

淬火速率对AA7108铝合金的微观结构和力学性能的影响

在480°C固溶温度对AA7108铝合金进行不同工艺的淬火。将合金连续冷却、淬火至中间温度（400,300和200°C）并保温不同时间,再进行工业两步人工时效处理,以获得最大强度（T6）。T6态淬火材料的拉伸试验表明,材料的强度很大程度上取决于冷却/保温时间。通过透射电子显微镜（TEM）观察材料中沉淀物结构来解释材料的力学性能差异。     

The effects of heat treatment condition and Si distribution on order-disorder transition in high Si steels

The decomposition and formation of ordered phases in steels with 5 to 6.5 %Si were investigated by a combined analysis of TEM and electrical resistivity measurements in order to determine the optimal heat treatment conditions for removal of ordered phases. TEM diffraction pattern study revealed that B2 ordered phase in 6.5 %Si steel was sufficiently dissolved by heat treatment at 850 °C for 1 h, and then rapidly re-formed during cooling. The critical cooling rate, above which the suppression of B2 phase formation was possible, increased rapidly with Si content higher than 5.6%. DO₃ phase appeared only in the case of as-cast samples containing Si content as high as 6.5%. The measurement of electrical resistivity change during the heat treatment showed that the atomic movement was substantially spurred above 800 °C, resulting in an active order-disorder transition. The removal of solidification segregation is necessary to reduce the amount of B2 ordered phase in the as-cast or hot-rolled state, to lower the heat treatment temperature for dissolution of B2 ordered phase, and to shorten the heat treatment time. This article is based on a presentation made in the 2003 Korea-Japan symposium on the “Current Issues on Phase Transformations”, held at Marriott Hotel, Busan, Korea, November 21, 2003, which was organized by the Phase Transformation Committee of the Korean Institute of Metals and Materials.     

High energy ion irradiation effect on light-emitting poly(3-methylthiophene) (P3MT) nanowires

Light-emitting poly(3-methylthiophene) (P3MT) nanowires with a diameter of ∼200 nm were fabricated using an electrochemical polymerization method based on an anodic alumina oxide (Al₂O₃) nanoporous template. The relatively high energy (3 MeV) Cl²⁺ ions were irradiated onto the P3MT nanowires with dosages from 1 × 10¹³ to 1 × 10¹⁵ ions/cm². To study the effect of high energy ion irradiation on P3MT nanowires, we measured UV/vis absorbance, Raman spectra, and laser confocal microscope photoluminescence (PL) on the nanometer scale. The relative atomic concentrations of carbon elements in the pristine and the 3 MeV Cl²⁺ ion-irradiated P3MT nanowires were investigated through XPS experiments. As the dosage of the 3 MeV Cl²⁺ ion irradiation increased, we observed that the P3MT nanowires changed to a partially carbonized form, and that the PL efficiency of the systems decreased.     

Electron irradiation effects on DC electrical performances of SiGe HBT in a comparison with Si BJT

The DC characteristics of SiGe HBT irradiated at different electron dose have been studied in a comparison with those of Si BJT. Generally, Ib and Ib - Ib0 increase, Ic, Ic - Ic0 and its /- transition Vbe as well as DC current gain β decreases with increasing dose; increase of I - Ib0 with increasing dose for Si BJT is much larger than that for SiGe HBT; β increases with Vbe or Ib, but decreases at Ib < 0.25 mA with 4, and congregates at higher dose; and a damage factor d(β) is much less at the same dose for SiGe HBT than for Si BJT. SiGe HBT has much better anti-radiation performance than Si BJT. Some anomalous phenomena for increase of Ic, Ic -Ic0,Ib- Ib0 and β at low dose have been found. Some electron traps have been measured. The mechanism of changes of characteristics is discussed.     

强脉冲离子束辐照对Ni_3Al合金表面的改性

采用X射线衍射、扫描电镜和电化学腐蚀等技术研究了 3种不同束流密度的强脉冲离子束辐照对Ni3 Al合金表面形貌与物相及电化学腐蚀性能的影响。结果表明 :IPIB辐照时 ,试样最外表面的温度远超过Ni3 Al合金的熔点 ,造成试样表面融化 ,从而清洁和抛光试样表面 ;随离子束流密度的增加 ,Ni3 Al合金表面的物相呈现规律性的变化 ,分别产生形变织构、部分非晶及新相 ,使Ni3 Al合金的抗电化学腐蚀性能得以提高     

时效处理SUS316L不锈钢中析出相的晶体结构和化学成分

研究了经1100℃固溶化处理和550℃,600℃及650℃,10000h时效处理后SUS316L不锈钢中的微观组织.利用透射电子显微镜对析出相的形状,大小,分布特征进行了观察.利用电子衍射技术对析出相的晶体结构进行了分析.利用分析电子显微镜能谱分析仪对析出相的化学成分进行了分析.结果表明：固溶后的SUS316L不锈钢经不同温度时效都有M23C6型碳化物的析出相存在.能谱分析显示M23C6析出相主要是由金属铬组成的碳化物.大部分M23C6碳化物分布在基体的晶界上,也有部分M23C6碳化物分布在基体的晶粒内部和晶体缺陷处.M23C6碳化物的大小和数量随着时效温度的升高而增加.     

表面处理对锆合金性能的影响

介绍了锆合金的表面处理技术,讨论了各种表面处理技术对于锆合金表层结构和合金元素分布的影响及改善锆合金性能的机理,提出了进一步研究的建议.     

The effects of ion beam treatment on the interfacial adhesion of Cu/polyimide system

In microelectronics packaging, the reliability of the metal/polymer interface is an important issue, as the adhesion strength between dissimilar materials is often inherently poor. The modification of polymer surfaces using Ar ion beam irradiation and RF plasma deposition has been commonly used to enhance the adhesion strength of the interface. In this study, the treatment of polyimide surfaces with Ar or O₂ ion beam irradiation and the DC magnetron sputtering of Cu films were adopted to prepare the specimens of Cu/polyimide systems. The results indicate that the peel strength increases as the Ar or O₂ ion beam irradiation energy increases at a fixed metal-layer thickness. Additionally, the treatment of polyimide surfaces using O₂ ion beam irradiation showed a higher peel strength than if Ar ion beam irradiation was utilized. This increase in peel strength mainly results from an increase in the surface roughness as well as an increase in the functional group on the polyimide film, both caused by ion beam irradiation.