氧化物弥散强化铁素体钢的电子辐照行为

本文利用超高压电子显微镜进行电子辐照实验，分析了我国试制的氧化物弥散强化（ＯＤＳ）铁素体钢的辐照行国．在６７０－７２０Ｋ下辐照时观察到了辐照空洞的形成．辐照条件为７２０Ｋ，９ｄｐａ时的辐照肿胀率小于０．１％．同时在电子衍射图样中发现了明显的衍射环，分析表明这些衍射环的出现是由于电子辐照促进了Ｙ２Ｏ３微细相形成的缘故．     

氧化物弥散强化铁素体钢的电子辐照行为SCIEI

本文利用超高压电子显微镜进行电子辐照实验，分析了我国试制的氧化物弥散强化（ＯＤＳ）铁素体钢的辐照行国．在６７０－７２０Ｋ下辐照时观察到了辐照空洞的形成．辐照条件为７２０Ｋ，９ｄｐａ时的辐照肿胀率小于０．１％．同时在电子衍射图样中发现了明显的衍射环，分析表明这些衍射环的出现是由于电子辐照促进了Ｙ２Ｏ３微细相形成的缘故．     

He对低活性Fe-Cr-Mn(W,V)合金辐照产生点缺陷行为的影响

采用超高压电镜与离子加速器相连结的复合辐照装置，研究了注He对低活性Fe-Cr-Mn(W，V)合金辐照产生的点缺陷及二次缺陷行为的影响．实验结果表明：辐照初期形成的点缺陷与He相互作用，进而影响二次缺陷(位错、位错环和空洞)的形成；He明显促进位错密度增大和空洞核心形成，并导致空洞肿胀增加．对辐照产生的点缺陷与He相互作用的机理进行了理论分析。     

球化高碳钢薄板在多向应力状态下的氢脆

在从单向拉伸到双向等应力拉伸的应力状态范围内进行了球化高碳钢薄板氢脆的研究。测定断口处局部，断裂就变表明，在双向等应力拉伸中氢所引起的塑性损失最大。金相和断口检测结果表明，充氢和未充氢材料的断裂都是空洞形核，空洞长大，和空洞连通的结果。氢加速这三个塑性断裂过程，特别是双向等应力拉伸应力状态下，氢的影响更为显著。     

氢致脆断的TEM原位拉伸观察

通过对预充氢３１０不锈钢薄膜在透射电镜下的原位拉伸观察，并和不含氢试样的结果相比较，研究了氢在韧－脆转变中的作用及氢致脆断机理，结果表明，预充氢的３１０不锈钢试样在拉伸过程中从裂发射大量位错，平衡后形成无位错区；纳米级微裂纹优在ＤＦＺ中形核，微裂纹不钝化为空洞，而是通过多个微裂纹的形核及相互连接导致裂纹的脆性扩展，即氢使奥氏体不锈钢由韧变脆的根本原因是氢抑制了ＤＦＺ中纳米级微裂纹向空洞的转化。     

0.29V-0.09Ta RAFM钢辐照条件下空洞演化的实验和理论研究（英文）

为研究辐照条件下空洞的演化,分别在200,350和550℃对低活化铁素体/马氏体钢(RAFM)进行He离子辐照。实验结果显示,辐照损伤沿深度呈钟型分布,空洞的尺寸和密度均与空位产生率正相关。随着辐照温度升高,空洞的尺寸增大,密度降低,高温下可以观察到空洞在晶界的聚集和无空洞区(VDZs),在550°C可以观察到方形空洞。使用相场模型模拟空洞的演化机制,模拟结果显示,辐照条件下空洞演化可以分为孕育、形核和生长3个阶段,空洞界面能的各项异性是空洞形状的可能原因。     

蠕变空洞形核研究

基于空位扩散和凝取的物理学背景，应用修正逾渗模型从微观层次上描述空洞形核过程，出空洞形核时间表达式。讨论了空洞形核的地点和方式。对二３维点阵空洞表核过程进行了计算机模拟。     

Fe3Al氢致开裂和应力腐蚀的TEM原位观察

利用恒位移加载台，在ＴＥＭ中原位观察了Ｆｅ３Ａｌ薄膜试样充氢和应力腐蚀前后裂尖位错组态的变化，以及位错对裂纹形核的影响。结果表明，氢能促进裂尖发射位错，促进位错的增殖和运动，并使无位错区增大，当位错发射，运动发展到临界状态时，就会导致氢致裂纹的形核与的扩展。对氢促进位错发射，增殖和运动的原因进行了探讨。     

0.29V-0.09Ta RAFM钢辐照条件下空洞演化的实验和理论研究

为研究辐照条件下空洞的演化,分别在200 °C, 350 °C和550 °C对低活化铁素体/马氏体钢(RAFM)进行He离子辐照。实验结果显示辐照损伤沿深度呈钟型分布,空洞的尺寸和密度均与空位产生率正相关。随着辐照温度升高,空洞的尺寸增大,密度降低,高温下可以观察到空洞在晶界的聚集和无空洞区(VDZs),在550 °C可以观察到方形空洞。使用相场模型模拟空洞的演化机制,模拟结果显示辐照条件下空洞演化可以分为孕育、形核和生长三个阶段,空洞界面能的各项异性是空洞形状的可能原因。     

Ti3Al金属间化全物氢致解理断裂及其机理

Ｔｉ－２４Ａｌ－１１Ｎｂ合金在室温下恒载荷动态充氢以及交变载荷动态充氢时，氢通过促进裂纹在滑移面上的解一，促进了裂纹扩散，不连续的氢致解理裂纹优先在α２相形核，α２／β相界面是裂纹扩展的有效障碍，氢通过促进裂尖位错的发射、解理微裂无位错区（ＤＦＺ）的形核以及解理裂纹，导致氢致解理断裂。     

Hydrogen migration in electron irradiated Pd based dilute alloys around the 50 K anomaly

The migration of hydrogen in Pd–1 at.% Fe–H and Pd–1 at.% Ag–H alloys is investigated by electrical resistivity measurement around 50 K. The disordered hydrogen atoms are introduced by electron irradiation with 0.5 MeV electrons below 15 K. The disordered atoms order by migration of hydrogen atoms during the heating-up of the specimens. The recovery curves of electrical resistivity have two sub-stages for electron irradiated specimens and one stage for fast cooled specimens. The migration energy of hydrogen is obtained from the kinetic analysis of the resistivity change due to the ordering, using the cross-cut method for the electron irradiated specimen and fast cooled specimen. The obtained value of the migration energy for the low temperature stage is smaller than that for the high temperature stage. The value for the high temperature stage is similar to the energy for the case of fast cooling. The difference between the hydrogen atoms disordered by irradiation and that by fast cooling is discussed for Pd based alloys.     

Effects of implantation temperature and volume flow rate ratio of nitrogen and hydrogen on nitrogen concentration distribution, mechanical properties, fatigue life, fracture toughness, and tribological behavior of plasma-nitrided P20, 718 and 420 steels

In the present study, three steel materials, AISI P20 DEM NO.3, ASSAB 718 and AISI 420, were selected as the mold substrate materials in plastic injection forming. The plasma immersion ion implantation (PIII) system with an electron cyclotron resonance microwave source was applied to prepare the specimens by varying the implantation temperature (400 °C, 460 °C and 520 °C) and the volume flow rate ratio (4:1, 1:1 and 1:3) of nitrogen to hydrogen in the gas mixture (N₂:H₂). For the specimens with the same substrate material, the mean hardness was either invariant to or lowered by increase in the total penetration depth of nitrogen. The hardness was lowered by increasing the distance of the peak position of nitrogen concentration from the implantation surface. Both the fracture toughness and the fatigue life of a specimen at the nitrided layer were elevated by increasing the implantation temperature. The most significant increase in each of these two mechanical properties due to the temperature increase gives rise in the P20 specimens. Varying the N₂:H₂ ratio shows a fatigue life sequence of (FL)_4:1 > (FL)_1:3 ≥ (FL)_1:1 for all three substrate materials. X-ray diffraction (XRD) was applied to determine the phase structures at the nitrided layer which was formed by changing either the implantation temperature or the N₂:H₂ ratio. The (α-Fe + CrN) phase in the nitrided later can elevate the fatigue life and fracture toughness of the specimen. However, the increase in the hardness is due to the combined effect of all main phases formed in the nitrided later. The scratch wear resistance of a specimen with ion implantations is significantly enhanced compared with that exhibited in the “pure” specimen (without nitrided layer). However, most of the specimens with ion implantations showed severer adhesive wear than corresponding “pure” specimens.     

In situ observations on effects of hydrogen on deformation and fracture of A533B pressure vessel steel

External hydrogen gas atmospheres enhanced dislocation motion, multiplication of dislocations, and dis-location source activation under applied loading during in situ high-voltage electron microscopy (HVEM) observations of A533B pressure vessel steel. However, in both vacuum and hydrogen atmos-pheres, fracture occurred in a ductile manner in specimen areas transparent in the 1000-keV HVEM. The principal effect of the hydrogen atmosphere was to decrease the stress required for deformation near the crack tip and for crack propagation. Deformation at the crack tip was highly localized in both atmos-pheres, and a yielding strip plastic zone, analogous to the Dugdale-Barenblatt model for crack growth, formed ahead of the crack tip. The crack tip plasticity was confined to this strip. Inside the yielding strip, final cracking occurred through a sliding-off mechanism in the thin areas of the HVEM specimen. In the thicker areas of the specimen, where the yielding strip ahead of the crack was no longer transparent, crack tip blunting and void/microcrack formation ahead of the main crack tip could be observed directly. Crack tip blunting occurred by a two-corner mechanism, and further crack growth initiated by strain lo-calization at one of the crack tip vertices. Also void/microcrack formation ahead of the main crack tip was operative and resulted in coalescence into the main crack tip along the anticipated shear bands. Frac-tography of the thicker areas showed a ductile, dimpled fracture mechanism both in vacuum and hydro-gen atmospheres. Technical Research Centre of Finland, Metals Labo-ratory, SF-02150 Espoo, Finland     

热氢处理对TA15钛合金组织及性能的影响

采用真空气相热氢处理炉得到不同氢含量的TA15钛合金试样,利用扫描电镜、夏比冲击设备以及带传感器的机床等对不同氢含量的钛合金试样进行切削力获取及组织形貌观察,研究热氢处理过程中不同氢含量TA15钛合金试样的组织结构演变和力学性能规律.结果表明,TA15钛合金试样热氢处理后会出现不同程度的组织细化;热氢处理后的TA15钛...     

Improving corrosion resistance of magnesium-based alloys by surface modification with hydrogen by electrochemical ion reduction (EIR) and by plasma immersion ion implantation (PIII)

Magnesium-based hydrides are well known that they have a high hydrogen-storage capacity. In this study, two different methods have been provided for hydrogen surface modification of high purity magnesium (hp Mg) and AZ91 magnesium alloy. One was electrochemical ion reduction (EIR) of hydrogen from an alkaline electrolyte on such Mg-based cathode. The other was plasma immersion ion implantation (PIII or PI³) into Mg-based substrate. The depth profile of H-modified surfaces was described by Auger electron spectroscopy (AES) and by secondary ion mass spectrometry (SIMS) measurements. Corrosion testing was carried out in Avesta cell by potentiodynamic polarisation in chloride-containing aqueous solutions of pH 7 and pH 12. A greatly significant improvement in the corrosion resistance of H-modified surfaces was verified.     

Ta离子注入对铝青铜耐磨性能的影响

采用俄歇电子能谱仪分析Ta离子注入铝青铜合金的Ta、Cu和Al元素分布,利用显微硬度仪测量注入Ta离子铝青铜的显微硬度,用摩擦磨损试验机分析QA19-4铝青铜的摩擦系数和磨损质量损失.结果表明:随Ta离子注入剂量的增加,铝青铜中的Ta原子浓度升高,离子注入深度超过100 nm,显微硬度显著增高,在距合金表面约60 nm深处硬度达到最大值;铝青铜的摩擦系数显著降低,单位时间内磨损质量损失显著减小,因此明显提高了舒j青铜的耐磨性能.     

电子辐照Fe-Cr-Ni奥氏体合金的空洞体胀与诱起晶界偏析的研究

本文用超高压电镜(HVEM)作为电子束源,研究了Fe-15％Cr-30％Ni合金电子辐照后,合金空洞体胀和诱起晶界偏析.实验结果证明:723K,最大剂量15dpa条件下,体胀量为0.62％.在晶界发生Cr贫化、Ni富化.随着辐照温度提高,晶界偏析程度增加,723K时Cr,Ni在晶界出现最大偏析峰,相应空洞体胀量也最大.结果表明,空洞形成和晶界偏析密切相关,本文提出了辐照诱起晶界偏析模型.     

氢对304不锈钢阳极行为的影响

<正> 虽然奥氏体不锈钢在42％MgCl_2沸腾溶液中的应力腐蚀并不是由氢致开裂引起的,但在应力腐蚀过程中生成的氢可以进入试样并可在裂纹前沿富集。为澄清进入试样的氢是否对阳极溶解过程产生促进作用,曾有人用失重法、晶间腐蚀和极化曲线变化等研究氢对阳极行为的影响,并得出氢促进阳极溶解的结论。应当指出,充氢试样的阳极电流包括了氢的氧化电流,因此充氢后阳极电流的增大并不证明氢促进了阳极溶解过程。虽然失重法能反映氢的促进作用,但只适用于腐蚀较为严重的情况。     

离子注入对铜失泽行为的影响

本文用表面光反射,电化学库仑还原、扫描和透射电子显微镜研究了经Cr、Ta和惰性气体离子注入后的高纯铜,暴露在含H_2S大气中的失泽行为。暴露试验是在H_2S浓度为0.006—6VPM,25℃和100％RH条件下进行的。结果表明,Cr、Ta离子注入显著地提高了铜的抗失泽能力,Xe离子注入效果较小,而Ar离子注入无改进效果。阴极还原曲线显示经Cr、Ta离子注入的试样上形成的失泽膜,比未经离子注入铜上形成的膜薄,其结构组成亦不同。电子衍射结构分析和扫描电镜(附WDAX)分析进一步证明,Cr离子注入抑制了铜表面膜中金属硫化物的形成。