Effect of temperature on the form change of a palladium plate during its one-sided saturation with hydrogen

Effect of temperature on the regularities and scale of form changes of a palladium plate has been studied in a cantilever mode of fixation of a specimen, during its one-sided saturation with hydrogen. The form change of the plate is confirmed to be developed in two stages. During the first short-time stage, the maximum form change (bending) of the plate is reached. The temperature dependence of the maximum bend of the plate is described by an extremal function. During the second stage, which is of substantially longer duration, a plate straightening takes place. At low temperatures, the residual steady-state bend of the plate is 20–30% of the maximum form change. As the temperature increases, the bend reversibility increases and at 320–350°C the phenomenon becomes completely reversible. The mechanism of form change is discussed, and its phenomenological analysis is given.     

Change in form of palladium plate during one-sided saturation with hydrogen: I. Effect of rate of increase in gaseous-hydrogen pressure

The effect of the rate of gaseous-hydrogen pressure rise on changes in the form of a palladium plate has been studied during its one-sided saturation with hydrogen in the ?? region of the Pd-H system under isothermal conditions at temperatures of 170?C320°C. The dependences of the principal characteristics of hydrogen-induced changes in the form of a plate on the rate of gaseous hydrogen pressure rise were determined. The decrease in the rate of increase in hydrogen pressure was found to lead to a decrease in the maximum bend of the plate.     

Experimental observation of a soliton-like moving swell on the surface of a palladium-hydrogen alloy

Upon additional saturation of a PdH_0.1 alloy with hydrogen under highly nonequilibrium conditions, moving coherently conjugate undulatory swells, (whose shape and character of motion resemble those of solitary translational waves—solitons) on the surface have been for the first time fixed and recorded on video tape. Based on modern concepts about the metal-hydrogen systems, the observed soliton-like moving swell and the mechanism of its formation and motion have been discussed. Emphasis has been placed on the fact that the incipient formation of soliton-like coherent moving swells is a special previously unknown mechanism of relaxation and leveling-off of internal stresses in metal-hydrogen alloys.     

Formation of hydrogen blister on AZ91 magnesium alloy during cathodic charging

The process of hydrogen blister formation on as-cast AZ91 magnesium alloy was investigated in 0.1 M NaOH solution using galvanostatic test. The results showed that cathodic charging of AZ91 alloy resulted in hydrogen blister formation, and blister rupture caused the nucleation and propagation of transgranular micro-cracks around the ruptured blister.     

Formation mechanism and wear behavior of gradient nanostructured Inconel 625 alloy

The formation mechanism and wear behavior of a gradient nanostructured (GNS) Inconel 625 alloy were investigated using SEM, TEM and ball-on-disc sliding wear tester. The results show that surface mechanical grinding treatment (SMGT) induced an approximately 800 μm-deep gradient microstructure, consisting of surface nano-grained, nano-laminated, nano-twined, and severely deformed layers, which resulted in a reduced gradient in micro-hardness from 6.95 GPa (topmost surface) to 2.77 GPa (coarse-grained matrix). The nano-grained layer resulted from the formation of high-density nano-twins and subsequent interaction between nano-twins and dislocations. The width and depth of the wear scar, wear loss volume, and wear rate of the SMGT-treated sample were smaller than those of untreated coarse-grained sample. Moreover, the wear mechanisms for both samples were mainly abrasive wear and adhesive wear, accompanied with mild oxidation wear. The notable wear resistance enhancement of the GNS Inconel 625 alloy was attributed to the high micro-hardness, high residual compressive stress, and high strain capacity of the GNS surface layer.     

钯合金与镍合金的真空钎焊工艺

探讨了真空钎焊钯合金与镍合金的工艺，并以探测器为例分析了其加热速率、保温时间、真空度和冷却速率对钎焊接头质量的影响，优化了其钎焊工艺参数。提出的钎焊工艺参数对生产具有重要的参考价值。     

The application of ultra-thin palladium alloy metal foils in gas-phase hydrogen separation or purification

Palladium and platinum metals or their alloys have been used in fuel cells as membranes for the separation and purification of hydrogen from other gases for more than 50 years. This technology has generated a great deal of interest with the recent growth of the fuel cell industry as an enabling technology in the future commercial application of a proton exchange membrane fuel cell system.     

Fracture mechanism of a laminated aluminum alloy plate during ballistic impact

The multilayered 7XXX series aluminum alloy was impacted by 7.62 mm ogival projectiles at velocities ranging from 787 to 851m·s~(-1). The deformed microstructure under various impacting velocities and fracture surfaces of different sections were investigated at different physical scales to determine the process of failure.Optical microscopy(OM),electron back-scattered diffraction(EBSD) and scanning electron microscopy(SEM) were used in the investigation. The results show that crater is constrained in the 7B52 front layer and two types of adiabatic shear bands which are transformed bands and deformed bands and different types of cracks are observed.Spall fracture is the significant failure mode of 7B52 front layer, and the resulting delamination leads to the presence of bending tensile fracture instead of the shear plugging.The ductile 7A01 layer blunts and deflects the spall crack tips, preventing the targets from full spall, and induces a constraint of 7A52 rear layer. The level of the constraint determines different fracture modes of 7A52 layer,accounting for the asymmetry of damage.     

应用稀土及激光熔覆工艺制备钴基合金梯度涂层

采用稀土变质及激光熔覆工艺在 2 0号钢基体上获得了钴基自熔合金梯度组织涂层。结果表明 ,2 0 4Co合金涂层组织为均匀的亚共晶 ,其组成相包括ε Co ,Co3 B ,M2 3 (C ,B) 6,Cr2 B及Co7W6化合物 ,平均硬度为HV10 70 ,比基体 (HV180 )高HV890 ,耐磨性与基体相比提高 1.5倍。在 2 0 4Co合金中加入 0 .6 %的稀土 ,可以获得梯度涂层。其组织由亚共晶向共晶连续过度 ,与前者相比 ,组成相增加了CeCr2 B4 ,最高硬度达HV12 0 4,比原合金高 12 .3%,耐磨性与基体相比提高近 2倍 ,比原合金提高了 2 5 %。     

宽板弯曲应变中性层内移及板厚变薄规律的探讨

利用数值模拟方法对宽板V形弯曲过程进行研究,确定了相对弯曲半径对应变中性层位置以及变薄系数的影响。结果表明:随着弯曲过程的进行,相对弯曲半径减小,应变中性层内移系数与相对弯曲半径符合指数函数模型,变薄系数与相对弯曲半径符合指数函数模型。     

熔融堆积成形过程温度场的模拟研究

为研究在不同咬合方式和不同咬合力下颌骨的受力情况,基于已有的头部CT数据,通过医疗软件Mimics提取下颌骨并建立三维模型,并对下颌骨进行重画网格、构造轮廓线、构造曲面片、构造格栅、拟合曲面等分析. 通过对正常的下颌骨以及3D打印钛合金植入物修复的下颌骨进行对比分析. 研究在不同咬合方式和不同咬合力的情况下,下颌骨的受力情况,分别得到下颌骨不同部位加载下的应力和位移分布情况. 结果表明,在3D打印钛合金植入物修复的下颌骨上加载成年男性前,后牙所能承受的最大咬合力时,下颌骨所受到的应力均小于正常下颌骨所受到的应力.     

Transverse stress-strain evolution during welding of thin aluminum alloy plate

The FE simulation results of transverse stresses and strains during welding of thin aluminum alloy plate arepresented.The results indicate that restraint condition is the main factor that determines whether or not hot cracking willoccur. With rigid restraint hot cracking(crater cracking) will occur at the arc-stopping end, and such cracking usuallywill not occur without external restraint. But under restraint-free condition it is easy for terminal cracks to occur.     

Formation of textural inhomogeneity in a Zn-1.1% Al alloy during superplastic deformation

The Zn-1.1% Al alloy with a strong rolling texture has been tested under the conditions of superplasticity. The samples were cut from a sheet 5 mm thick at an angle of 20° with the sheet plane. The material in the initial state was characterized by the absence of a texture gradient over the sample thickness. Deformation led to a substantial weakening of texture maxima inside the sheet and their retention at the surface. Estimate of intragrain slip revealed that the contribution from slip was greater in deeper layers and smaller at the sheet surface. The effect was explained by different conditions of accommodation of grain-boundary sliding at the surface and inside the sheet.     

Evolution of grain structure in AA2195 Al-Li alloy plate during recrystallization

1 Introduction Aerospace and aircraft industry has a great interest in developing new aluminum alloys with high performance. AA2195 Al-Li alloy, which has high strength, very strong and rapid natural aging capability, good fracture toughness, good weldabi…     

9Ni钢板热处理过程中的尺寸变化

为研究9Ni钢在热处理过程中的尺寸变化机理,在同一位置对热处理前后的9Ni钢板尺寸进行了测量。结果显示,钢板在一次和二次淬火前后其宽度和长度尺寸均发生增加,并且其膨胀率相近。分析认为,9Ni钢板尺寸发生变化的原因是淬火过程中钢板相变层的膨胀量超过未相变层的屈服应变,导致未相变层奥氏体发生塑性延伸。     

Formation of palladium nanoparticles under pulse current in a dimethylformamide solution

The morphology of palladium deposited by pulse electrolysis from dimethylformamide solutions of PdCl₂ on the surface of graphite and ITO glass was studied. The effect of the value of cathode potential and electrolysis duration on the sizes of particles and their distribution in the substrate was investigated. It was shown that, on the substrate surface, deposits with particle sizes of 30–350 nm are formed.     

3104铝合金热粗轧板的织构梯度及其对热压缩变形后退火织构演变的影响

采用X-ray衍射和光学显微镜对AA3104铝合金热粗轧板沿厚向的织构和组织进行研究。结果表明:热粗轧板中存在明显的组织和织构梯度现象;在表层及次表层,剪切织构占主导地位,表现为较强的旋转立方织构R-cube{001}110和{112}110织构,显微组织以再结晶组织为主;在中心层及过渡层,则以典型的形变织构(即Cu{112}111、S{123}634和Bs{011}211)及热变形流线组织为主;这种沿厚度方向的组织和织构梯度对热变形后再结晶织构也有很大影响,热粗轧板中原始的剪切织构有助于退火后立方织构的形成,而原始中心层的形变织构会促使热变形退火后产生{111}110剪切织构和P织构。     

On the wave propagation of concentration hydrogen disturbances in palladium

The mechanisms of the origin of moving hydrogen concentration inhomogeneities recently discovered in the Pd—H system are discussed. An exact wave solution to the nonlinear equation of diffusion for hydrogen in metals has been found. On the basis of this solution and approximate solution found earlier, a conclusion has been made that the basic reason for the appearance of moving inhomogeneities can be the interaction (attraction) of hydrogen atoms dissolved in the metal rather than internal “hydrogen-induced” concentration stresses.     

Changes in the grain and fine structures of palladium as a result of hydrogen phase naklep

Changes in the grain and fine structures of palladium that occur after the occurrence of reverse β → α hydride phase transformation in the metal are studied. It is shown that hydrogen treatment does not change the microstructure of palladium but strongly affects its fine structure. __________ Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 3, pp. 49–54, March, 2007.     

Formation and evolution of spherocrystals in a NiTiZrAlCuSi amorphous alloy

The microstructure of a NiTiZrAlCuSi bulk metallic glass was investigated by transmission electron microscopy (TEM) attached with energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). TEM results showed that some spherocrystals were embedded in the amorphous matrix, but XRD patterns from the sample did not reveal distinct diffraction peaks from the minor amount of spherocrystals. EDS analyses indicated that the composition of these spherocrystals was similar to that of the metallic glasses matrix. To further study the evolution of these spherocrystals, isothermal crystallization experiment was carried out using differential scanning calorimetry (DSC). DSC curves and XRD patterns reveal the microstructure difference of the sample at different heating times. TEM images record the evolution processes of the metastable spherocrystal and amorphous matrix.