Behavior of hydrogen and defects in zirconium under irradiation

The accumulation of hydrogen and defects in the E-125 zirconium alloy (Zr-2.5% Nb) is investigated. The hydrogen concentration is maximum on the surface of zirconium alloy samples after electrolytic hydrogenation. The hydrogen concentration decreases at a depth of about 0.5 μm and then gradually grows with increasing depth. The surface of the zirconium alloy is strengthened and becomes more fragile after hydrogenation. A plastic deformation of the zirconium alloy gives rise to traps with different binding energies of hydrogen. The primary type of traps, the binding energy, and the amount of hydrogen captured by traps depend on the deformation magnitude and the sequence of deformation and hydrogenation processes. High mobility of hydrogen in plastically deformed samples is observed under bombardment of the surface of the zirconium alloy by a helium ion beam with an energy of 2.34 MeV. The variation of the hydrogen concentration in the near-surface region of zirconium under ion bombardment depends on the extent of deformation: upon bombardment by helium ions, the hydrogen concentration in the near-surface region of the metal increases for deformations from 1 to 3% and decreases for deformations of 4 and 5%.     

Porous microstructures induced by picosecond laser scanning irradiation on stainless steel surface

A study of porous surfaces having micropores significantly smaller than laser spot on the stainless steel 304L sample surface induced by a picosecond regenerative amplified laser, operating at 1064 nm, is presented. Variations in the interaction regime of picosecond laser pulses with stainless steel surfaces at peak irradiation fluences(F_pk=0.378–4.496 J/cm²) with scanning speeds(v=125–1000 μm/s) and scan line spacings(s=0–50 μm) have been observed and thoroughly investigated. It is observed that interactions within these parameters allows for the generation of well-defined structured surfaces. To investigate the formation mechanism of sub-focus micropores, the influence of key processing parameters has been analyzed using a pre-designed laser pulse scanning layout. Appearances of sub-focus ripples and micropores with the variation of laser peak fluence, scanning speed and scan line spacing have been observed. The dependencies of surface structures on these interaction parameters have been preliminarily verified. With the help of the experimental results obtained, interaction parameters for fabrication of large area homogeneous porous structures with the feature sizes in the range of 3–15 μm are determined.     

强流脉冲离子束辐照对不锈钢耐腐蚀性能的影响

 利用强流脉冲离子束（HIPIB）对316L不锈钢进行了表面辐照处理,研究了HIPIB辐照对其在0.5mol/L H2SO4溶液中电化学腐蚀性能的影响。极化曲线测量结果表明,HIPIB辐照能够显著提高316L的抗腐蚀性能,自腐蚀电流对辐照次数的依赖性与自腐蚀电位相比明显较强。采用扫描电子显微镜（SEM）、X射线衍射（XRD）和电子探针（EPMA）分析辐照后试样表面形貌、表面层相结构和元素分布的变化。结果表明：HIPIB辐照使试样表面光滑化,表面层产生择优取向,且发生了杂质元素的选择性烧蚀,是316L不锈钢耐电化学腐蚀性能得以提高的主要原因。     

强流脉冲离子束辐照对不锈钢耐腐蚀性能的影响

利用强流脉冲离子束（HIPIB）对316L不锈钢进行了表面辐照处理,研究了HIPIB辐照对其在0.5mol/L H2SO4溶液中电化学腐蚀性能的影响。极化曲线测量结果表明,HIPIB辐照能够显著提高316L的抗腐蚀性能,自腐蚀电流对辐照次数的依赖性与自腐蚀电位相比明显较强。采用扫描电子显微镜（SEM）、X射线衍射（XRD）和电子探针（EPMA）分析辐照后试样表面形貌、表面层相结构和元素分布的变化。结果表明：HIPIB辐照使试样表面光滑化,表面层产生择优取向,且发生了杂质元素的选择性烧蚀,是316L不锈钢耐电化学腐蚀性能得以提高的主要原因。     

Behavior of structure defects and hydrogen in neutron-irradiated stainless steels studied by positron annihilation method

Measurements of angular distributions of annihilation photons are applied to investigating structural defects and hydrogen behavior in annealed, plastically deformed, and irradiated stainless steels. It is determined that the whole cycle of investigations performed by positron diagnostics helped in tracing the formation and evolution of the defect structure and hydrogen behavior in different kinds of steels being subjected to complex physical–mechanical influences such as plastic deformation, hydrogenation and irradiation by fission neutrons. The high sensitivity of the electron–positron annihilation method allowed understanding even of details of the changes of the crystalline structure of multi-component materials.     

Anisotropic explosions of hydrogen clusters under intense femtosecond laser irradiation

We report on measurements of ion energy distributions from hydrogen clusters irradiated by intense laser pulses of duration 40 and 250 fs. Contrary to the predictions of a simple Coulomb explosion model, we observe a pronounced spatial anisotropy of the ion energies from these explosions with the highest energy ions ejected along the laser polarization direction. The origin of the anisotropy is distinct from that previously seen in clusters of high Z atoms such as Ar and Xe. Furthermore, a measured increase in H+ ion energy when longer, lower intensity pulses are employed suggests that multiple-pass, vacuum heating of the cluster electrons is important in the deposition of energy by the laser.     

Behavior of absorption bands in pure quartz glasses under electron irradiation

In KS-4V, KU-1, and Corning 7980 glasses, the behavior of six individual absorption bands induced by the electron beam as its fluence F increases to 20 kJ/cm² are studied. The UV band amplitudes reached a quasi-steady level at F ≈ 4 −5 kJ/cm² in all glasses.     

Measurement of the hydrogen reduction on stainless steel produced by an argon glow discharge

The hydrogen content on a stainless steel surface has been reduced by an argon glow discharge to $\text{1}\text{6}$ of its original value. The absolute number of the hydrogen atoms has been measured using the H(¹¹B, α)2α reaction. The result is discussed in the context with the storage of ultra cold neutrons in material containers.     

Microstructure evolution on the surface of stainless steel by Nd:YAG pulsed laser irradiation

New structure phenomena with the grain sizes of 60 nm to 1 μm would be expected on the stainless steel surface by Nd:YAG pulsed laser irradiation. Nano-structures with various shapes and sizes were formed mainly during the solidification and most shapes of particles were diversiform according to different distances from the center of the spot. The morphologies were of equiaxed nano-particles and faceted hexagons. The surface re-solidification velocities have been estimated according to the numeral simulation of the thermal conditions. It was proved by the XRD that they were mainly consisted of γ-Fe and manganese oxides. The XPS results confirmed the EDS results that on the surface the alloy elemental composition in the outermost layer were rich in Mn and poor in Fe and in reverse in the center of the laser spot. Through observation of morphologies grown on the laser irradiated surfaces, direct evidence of growth mode transition from a continuous form to a lateral form was provided in one laser spot.     

连续激光重复加载下30CrMnSiA钢的反射率

利用双光束反射率测量装置,研究了连续激光重复加载作用下30CrMnSiA钢金属材料的反射率变化特性。通过激光加载、冷却然后再加载到更高的温度的辐照试验与激光单次辐照的结果比较,发现二次加载时材料表面的激光反射率与样品表面首次加载时达到的最高温度所对应的反射率基本一致,只有达到并超过首次加载时样品曾达到的最高温度后,样品表面的反射率才会再次发生变化,且变化趋势与单次完整加载时的路径重合。这表明样品表面的反射率与其达到的最高温度有关,进一步的研究结果表明,样品达到的最高温度与样品表面在最高温度下产生的氧化反应层有关,而这一氧化层在冷却过程和再加载过程不变化。     

Formation of surface gradient structural-phase states under electron-beam treatment of stainless steel

The structural-phase states of steel 08X18H10T (0.08% C, 18% Cr, 10% Ni, 1% Ti) subjected to pulse electron beam treatment in the regime of surface layer melting is investigated using the methods of optical and electron microscopy. The regularities of variations in the phase composition and the state of the defect substructure moving away from the irradiation surface up to a 200-μm depth are revealed.     

An ingenious approach of determining hydrogen isotope solubilities, diffusivities and permeabilities in GWHER-1 stainless steel

In this paper, by using an ingenious method, the hydrogen isotope solubilities and diffusivities in GWHER-1 stainless steel have been determined by a vacuum heating degassing approach at the temperature range of 597-1022 K on a set of specimens with different sizes previously charged for 24 h under a hydrogen isotope pressure of 105 Pa in the temperature range of 800-1000 K. The permeabilities are then derived from the relation Φ = DKs. It is found D = 1.52 ×10^-6exp（-54100/RT）, Ks = 2.2×10^-exp（-5400/RT） and Φ = 3.3 ×10^-12exp（-59500/RT） for hydrogen, where Ks （Sieverts＇ constant） is given in Pa^-1/2, D in m2.s^-1.Pa^-1/2, T in K and R=8.31 J.mol^-1.K^-1. By taking isotope effects into account, the corresponding Arrhenius relations for deuterium and tritium are also deduced.     

Amorphous stainless steel coatings prepared by reactive magnetron-sputtering from austenitic stainless steel targets

Stainless steel films were reactively magnetron sputtered in argon/methane gas flow onto oxidized silicon wafers using austenitic stainless-steel targets. The deposited films of about 200 nm thickness were characterized by conversion electron M?ssbauer spectroscopy, magneto–optical Kerr-effect, X-ray diffraction, scanning electron microscopy, Rutherford backscattering spectrometry, atomic force microscopy, corrosion resistance tests, and Raman spectroscopy. These complementary methods were used for a detailed examination of the carburization effects in the sputtered stainless-steel films. The formation of an amorphous and soft ferromagnetic phase in a wide range of the processing parameters was found. Further, the influence of the substrate temperature and of post vacuum-annealing were examined to achieve a comprehensive understanding of the carburization process and phase formation. P. Schaaf’s former affiliation: II. Physikalisches Institut, Universit?t G?ttingen, Friedrich-Hund-Platz 1, 37077 G?ttingen, Germany.     

Growth of large microcones in steel under multipulsed Nd:YAG laser irradiation

We report the growth of conical microstructure arrays on a stainless steel substrate under multi-pulsed Nd:YAG laser irradiation (wavelength of 1.064 μm, pulse duration of 300 ns, repetition rate of 5 kHz) at atmospheric air pressure. The average period of microcones is 70 μm, and they protrude 50–60 μm above the substrate. At an air pressure of 1 Pa, the well-defined conical shape is lost and the resulting microstructure shows a smaller period and height. At 10^-3 Pa, only small protrusions separated by about 5 μm are observed. The different mechanisms involved in the growth of conical microstructures are discussed. PACS 42.62.-b; 81.65.-b     

Water irradiation by high-frequency ultrasonic wave: effects on properties of passive film formed on stainless steel

In this paper an aqueous solution was irradiated with a 1.63MHz ultrasonic wave. It is shown that if stainless steel can passivate under dynamic polarization in this medium, under static polarization, the latter does not show any repassivation behaviour with time. This is attributed to a diminution of the diffusion layer thickness that is developed at the electrode/electrolyte interface, which is associated with a production of H(2) species by sonolysis and which maintains reductive conditions at the interface. The oxide film formed under ultrasonic irradiation for 1h at a passive potential of+0.2V(SCE) shows an early stage of passivation and an increased disordered state, which implies a considerable decrease in the corrosion resistance behaviour of the sample. The polarization resistance of the stainless steel R(p) is divided by a value of 4.5 under ultrasonic conditions.     

Study of plastic deformation and proton irradiation influence on phase transitions in C18N9T stainless steel

Transmission and post-nuclear-reaction emission Mössbauer spectroscopy was used for investigation of radiation effects and plastic deformation influence on C18N9T steel. The rolled foil was annealed in 10^?6 Torr vacuum at 870 K during 2 hours and was irradiated by 30 MeV protons at current density of 0.8μ A up to doses of 5×10¹⁷ cm^?2 on the isochronous cyclotron at the liquid nitrogen cooling of the target. The Mössbauer spectra obtained before and after the sample irradiation in transmission geometry are identical. The emission spectrum is analogous to the spectrum of the plastically deformed sample. It is concluded that during irradiation in the steel the processes take place which are similar to those at plastic deformation and connected with redistribution of the alloy component atoms.     

Initial oxidation of duplex stainless steel

Three different techniques were used to produce thin oxide layers on polished and sputter-cleaned duplex stainless-steel samples. These samples were exposed to 10⁻⁵ mbar of pure oxygen inside the vacuum chamber, exposed to ambient conditions for 24 h, and plasma oxidized. The oxide layers thus produced were analysed using XPS depth profiling in order to determine the oxide layers’ compositions with depth. We found that all the techniques produce oxide layers with different traces of metallic components and with the maximum concentration of chromium oxide shifted towards the oxide-layer-bulk-metal interface. A common characteristic of all the oxide layers investigated is a double-oxide stratification, with regions closer to the surface exhibiting higher concentrations of iron oxide and those more in-depth exhibiting higher concentrations of chromium oxide. A simple non-destructive Thickogram procedure was used to corroborate the thickness estimates for the thinnest oxide layers.     

充氚不锈钢中氦行为的实验研究

对充氚和未充氚的抗氢-2不锈钢(HR-2)样品进行退火处理,利用正电子湮没寿命谱技术以及金相检验技术探讨不锈钢中氦和微缺陷的相互作用行为.未充氚样品中,影响正电子寿命值的主要因素为杂质元素在晶界的析出.充氚样品实验中,退火温度小于300℃时,正电子寿命值的增加说明了氦泡的形成过程为非热形成,通过“冲出位错环”机制形成及长大;退火温度在300~600℃之间,充氚样品正电子寿命值的降低以及He的跃迁概率的计算结果,说明He原子通过热迁移至晶界;退火温度大于600℃时,热平衡空位浓度的计算结果以及正电子寿命值的增加说明热平衡空位开始发挥作用.     

Proton-induced grain boundary segregation in stainless steel

Abstract

A technique is developed which addresses the problem of irradiation assisted stress corrosion cracking of stainless steels in light water reactors using high energy protons to induce grain boundary segregation. These results represent the first grain boundary segregation measurements in bulk produced by proton irradiation of stainless steel. The technique allows the study of grain boundary composition with negligible sample activation, short irradiation time, rapid sample turnaround and at minimal cost. Scanning Auger electron microscopy is used to obtain grain boundary composition measurements of irradiated and unirradiated samples of ultra high purity (UHP) type 304L stainless steel and UHP type 304L steels with the additions of phosphorus (UHP + P) and sulphur (UHP + S). Results show that irradiation of all three alloys causes significant Ni segregation to the grain boundary and Cr and Fe away from it. Irradiation of the UHP + P alloy also results in segregation of P at the grain boundary from 5.3 to 8.7 at %, over 80 times the bulk value. No radiation-induced grain boundary segregation of S was measured in the UHP + S alloy. Results also indicate that the presence of P or S may enhance radiation-induced segregation of major alloying elements at the boundary. Comparison of irradiated and unirradiated regions of the UHP + P alloy indicate that while a prior thermal treatment segregates P to the grain boundary to 5.3 at %, the major element concentrations at the grain boundary are completely different from those under irradiation.