Thermal Desorption Spectroscopy Analysis Research Articles

Evaluation of hydrogen embrittlement susceptibility of underwater laser direct metal deposited 316L stainless steel

Underwater laser direct metal deposition (UDMD) shows great application potential in underwater high-performance repair. The susceptibility of underwater repaired components to hydrogen embrittlement (HE) is not extensively researched yet. In this study, HE in 316L stainless steel repaired by UDMD is systematically investigated and compared with in-air direct metal deposited (DMD) 316L and conventionally manufactured (CM) 316L. The experimental results show that the high cooling rates involved in UDMD contribute to a “austenite-ferrite” solidification mode. The cellular structure with a high-density of dislocations increases the tensile strength of as-built UDMD 316L. Thermal desorption spectroscopy analysis reveals that the hydrogen concentrations are similar for 316L manufactured by three processing methods, suggesting that the complex microstructural features by UDMD and DMD do not provide additional H-trapping sites. SSRT results show that the HE susceptibility is in the sequence: CM 316L (30.7%) > UDMD 316L (15.1%) > DMD 316L (9.6%). Compared with CM 316L, the stable cellular structure and higher stability towards martensitic transformation of as-built 316L are beneficial for the HE resistance. In the hydrogen-charged UDMD 316L, the hydrogen-assisted dislocation movement and mechanical twinning formation enhance the localized plasticity and induce cracking. The micron-sized oxide particles and micro-pores further contribute to the fast decohesion of interfaces in the presence of hydrogen. Those combined effects lead to the reductions in tensile strength and elongation of the hydrogen-charged UDMD 316L.

Influence of high-temperature thermal annealing on paramagnetic point defects in silicon-rich silicon nitride films formed in a single-wafer-type low-pressure chemical vapor deposition reactor

The influence of high-temperature thermal annealing on silicon dangling bonds called K centers in Si-rich silicon nitride films grown in a single-wafer-type low-pressure chemical vapor deposition reactor with the SiH2Cl2-NH3 system at 750 °C has been investigated by combining thermal desorption spectroscopy (TDS), Fourier transform infrared spectroscopy-attenuated total reflection, spectroscopic ellipsometry, and electron spin resonance. In the TDS analysis, H2 desorption from the nitride films was detected above about 600 °C. It is found that thermal annealing at 750 and 900 °C caused a slight decrease in the K center density and a change in the g value of K centers, which are considered to be caused by changes in the atomic structure of the nitride films. On the other hand, thermal annealing at 1050 °C resulted in a substantial decrease in the K center density and the generation of paramagnetic defects with unprecedented characteristics. The findings in this study are expected to provide important guidelines for the design of manufacturing processes of nonvolatile memories.

Dispersion Stability of Inorganic Powders Harnessed to Mosaic Surface Ligands via Multifit Hansen Solubility Parameters.

This study assessed the dispersion stability of industrial carbide/oxide powders that have mosaic surfaces comprised of multiple surface ligands. A large number (∼50) of probe liquids were used with an aim to effectively explain the data within the Hansen solubility parameter (HSP) framework. The proposed log-fit method, complemented by multi-HSP analysis featuring harmonic-mean-mixing HSPs, significantly improved the fit to experimental results for various mosaic-surface powders composed of complex surface ligands. X-ray photoelectron spectroscopy and thermal desorption spectroscopy analyses were employed synergistically to decipher the surface ligands of these mosaic-surface powders, which facilitated credible identification and quantification of the surface ligands. These results are in good agreement with the surface ligands and their coverage as determined by the multi-HSP analysis. Consequently, when it comes to characterizing powder surfaces, dispersion stability measurements paired with multi-HSP analysis are superior to conventional XPS and TDS analyses in terms of both topmost surface sensitivity and practicality.

Germanium nanostructures by helium plasma irradiation

The effects of helium plasma irradiation, which has been widely studied on metals, on germanium have been experimentally investigated. The irradiation temperature ranges from 430 to 720 K, and the incident ion energy ranges from 30 to 100 eV. From the scanning electron microscope (SEM) observation, it was found that various morphological changes including pits, nanocones, nanopillars, and roughened surfaces occur. The spatial scale of the morphological change was analyzed by applying fast Fourier transform to SEM micrographs. Thermal desorption spectroscopy analysis suggests that He atoms implanted on Ge play major roles in forming roughened surfaces at a surface temperature higher than 500 K.

Influence of sample extraction location on thermal desorption spectroscopy from a heat-resistant 13CrMo4-5 steel plate and correlation with microstructure features

Thermal desorption spectroscopy (TDS) is a highly sensitive and widely used method to directly measure the total hydrogen concentration and indirectly assess the hydrogen trapping sites and mechanisms from the spectra features in steels. Thus, there is a need to investigate the influence of sample location from a 5 mm plate of hot-rolled heat-resistant structural steel on TDS spectra. Via a new highly sensitive and specific correlation coefficient (microToH), the TDS results are correlated with low-angle grain boundaries volume fraction, grain size with different misorientation thresholds, microhardness, and geometrically necessary dislocations at different densities.The results indicate that sample location influences 133 % and 62 % in the hydrogen desorption of peak 1 (at 515 K), and total hydrogen concentration via the influence of peak 2 (at 634 K), respectively. Thus, sample location needs to be considered as one relevant aspect in a research plan based on TDS analysis. The influence on peak 3 (at 762 K) was found to be negligible as it is related to the first exothermic peak of the heating cycle, associated with carbide precipitation phenomena. The individual grain analysis performed with high-resolution adaptive DMM and GND maps emphasises the accumulation of the deformation in the ferritic domain at the vicinity of the pearlite structures.

In Situ Study of Hydrogen Accumulation in the E110 Zirconium Alloy during Gas-Phase Hydrogenation by the Methods of Thermal Desorption Spectroscopy and Synchrotron X-Ray Diffraction Analysis

In Situ Study of Hydrogen Accumulation in the E110 Zirconium Alloy during Gas-Phase Hydrogenation by the Methods of Thermal Desorption Spectroscopy and Synchrotron X-Ray Diffraction Analysis

Effect of exposure of W-D co-deposited films to air on deuterium content in the films

The deuterium loss from W-D co-deposited films after exposure to atmospheric air (∼50 % humidity) for 1, 24 and 576 h has been investigated for 50 nm, 250 nm, and 750 nm thick films. Approximately 50 % and 75 % of deuterium is lost after 24 h and after 576 h, respectively. The rate of deuterium loss is similar for thin and thick films. Significant amount of protium is trapped from air during exposure, which releases in H2 and H2O during thermal desorption spectroscopy analysis. Even after 24 days in air, the films do not transform into tungsten oxide.

On the Change in Hydrogen Diffusion and Trapping Behaviour of Pearlitic Rail Steel at Different Stages of Production.

To avoid hydrogen flaking in rail production, it is of crucial importance to understand the differences in hydrogen diffusion and trapping between different production steps. Therefore, as-cast unfinished material was compared with two finished rails, hot-rolled and head-hardened, using electron backscattered diffraction (EBSD), electrochemical permeation, and thermal desorption spectroscopy (TDS). A significant increase in dislocation density was in the head-hardened rail compared with the other material states. This leads to an effective hydrogen diffusion coefficient of 5.8 × 10-7 cm2/s which is lower by a factor of four than the diffusion coefficients examined in the other states. Thermal desorption spectroscopy analyses show a clear difference between unfinished and finished rail materials. While a peak in activation energy between 32 and 38 kJ/mol is present at all states, only as-cast unfinished material shows a second peak with an activation energy of 47 kJ/mol, which is related to microvoids. The results show that in the investigated material, the effect of increasing dislocation density has a stronger influence on the effective diffusion coefficient than the presence of a second active trapping site.

Effects of the microstructure and reversed austenite on the hydrogen embrittlement susceptibility of Ni-Cr-Mo-V/Nb high-strength steel

The effects of the microstructure and reversed austenite (RA) on the hydrogen embrittlement (HE) behavior were investigated in NiCrMoV/Nb high-strength steel prepared using three different heat treatments. The quenching and tempering (QT) steel showed a noble HE resistance for the lowest hydrogen diffusion and maximum apparent hydrogen concentration compared to quenching (Q) steel and quenching, lamellarizing, and tempering (QLT) steel. Thermal desorption spectroscopy (TDS) analysis confirmed that RA had an activation energy of 32.5 kJ/mol which indicates a stable trapping site. The QLT steel containing more RA exhibited a higher HE susceptibility, suggesting that RA degrades the HE resistance.

Hydrogen embrittlement behavior in FeCCrNiBSi TRIP steel

The effect of plastic deformations on the hydrogen embrittlement (HE) of transformation-induced plasticity (TRIP) steel was studied. In situ tensile tests showed that with increasing hydrogen current density, total elongation loss was raised to 36.8% as compared to an uncharged specimen. The electron backscatter diffraction (EBSD) observation indicated that hydrogen charging decreased stacking fault energy (SFE), resulting in the formation of more α′- martensite by both indirect and direct transformation. The α′- martensite volume fraction at the same degree of deformation in uncharged and charged samples was 31% and 39%, respectively. With plastic deformation, reversible trap sites were raised because of the increased dislocation density and the formation of α′- martensite, which was obtained from EBSD characterization and had a good correlation with the results of the thermal desorption spectroscopy (TDS) analysis.

Reassessment of tritium content in CFC tiles exposed to the JET D-T campaign in 1997

• In 2019 two MkIIA divertor tiles (6IN3 and 4BN4) exposed during DTE1 were retrieved at CCFE for Thermal Desorption Spectroscopy (TDS) and pyrolysis analyses. A set of samples were prepared using a coring technique. The highest tritium (T) inventories were found in the shadowed corner of the inner divertor due to asymmetric deposition. TDS analyses indicated that T is desorbed at rather high temperatures with maximum release peaks at ∼590 and 820 o C. T amounts were also investigated as a function of depth from the tile surface up to a depth of ∼4.5mm and T was detected at these depths. Comparison was also made with old results obtained with full combustion technique and PIN-diode method a few years after the DTE1 experiment, allowing for the natural decay of T. Our results agree within a factor of ∼3 with these results. In 2019 two MkIIA divertor tiles (6IN3 and 4BN4) exposed during DTE1 were retrieved at CCFE for Thermal Desorption Spectroscopy (TDS) and pyrolysis analyses. A set of samples were prepared using a coring technique. The highest tritium (T) inventories were found in the shadowed corner of the inner divertor due to asymmetric deposition. TDS analyses indicated that T is desorbed at rather high temperatures with maximum release peaks at ∼590 and 820 o C. A few samples were reannealed at 850 o C using the same heating procedure and it turned out that a further ∼40-50 % of T was still released indicating that the annealing procedure used does not empty the sample completely. Pyrolysis results for thin disks cut from the surface of the tile were somewhat higher than the corresponding TDS results. T amounts were also investigated as a function of depth from the tile surface up to a depth of ∼4.5mm and T was detected at these depths. Comparison was also made with old results obtained with the pyrolysis technique and a PIN-diode method a few years after the DTE1 experiment, allowing for the natural decay and off-gassing of T. Our results agree within a factor of ∼3 with these results.

On the role of the stacking fault energy in the beneficial effect of aluminium on the hydrogen embrittlement sensitivity of twinning-induced plasticity (TWIP) steel

The hydrogen embrittlement sensitivity of three twinning-induced plasticity steels is investigated. A reference TWIP steel (18Mn-0.6C) is compared to an aluminium added TWIP steel (18Mn-0.6C-1.5Al) and a TWIP steel with an increased manganese content (24.5Mn-0.6C), exhibiting an identical stacking fault energy as the aluminium added material. As such, the importance of the stacking fault energy in the reduction of the hydrogen embrittlement sensitivity with aluminium addition is evaluated, which is considered as one of the possible underlying mechanisms. Through thermal desorption spectroscopy analysis, it is shown that both aluminium and manganese addition increase the hydrogen solubility while the hydrogen diffusivity is increased by manganese addition and decreased by aluminium addition. These effects can be considered as the bulk effects of both alloying additions on the hydrogen properties. With respect to the mechanical properties, aluminium addition leads to the expected increased resistance to hydrogen while manganese addition reduces the hydrogen resistance, despite the equal stacking fault energy. The aluminium added TWIP steel shows increased resistance to hydrogen-assisted crack initiation and propagation suppressing intergranular fracture in the presence of hydrogen. On the contrary, the increased manganese content increases the tendency for intergranular cracking in the presence of hydrogen. The critical hydrogen concentration might therefore be higher with the addition of aluminium.

Evaluation of hydrogen diffusion and trapping in nickel Alloy 625 by thermal desorption spectroscopy

This study presents hydrogen diffusion and trapping in the nickel Alloy 625 by employing the hot extraction test and the thermal desorption spectroscopy (TDS) analysis. Combined with electrochemical permeation test, the impact of grain size and grain boundary carbide on hydrogen diffusion are investigated. The results manifeste that the effective hydrogen diffusivity can be expressed as D=1.03×10−7exp(−46.44kJmolRT)m2/s for the sample with a grain size of ∼8 μm. The diffusion activation energy ED for hydrogen is determined as 42.05–48.10 kJ/mol. The activation energy E associated with interstitial sites/elastic field of dislocations and reversible traps is 17.92–20.73 kJ/mol and 24.87–27.13 kJ/mol, respectively. Moreover, the reduction in grain size and the presence of grain boundary carbide can lower hydrogen diffusivity by locally changing the diffusion and trapping behavior of hydrogen.

A comparative study on the hydrogen dissolution and release behaviors in the zirconate proton conductors by TDS and TMAP4 analysis

Proton-conducting oxides are potential materials for electrochemical devices such as fuel cells, hydrogen pumps, hydrogen sensors, and the tritium purification and recovery system in nuclear fusion reactors. The hydrogen concentration in oxide materials is important, but its precise measurement is difficult. In this study, thermal desorption spectroscopy (TDS) was used to investigate hydrogen dissolution and release behavior in proton-conducting oxides, yttrium (Y), and cobalt (Co) doped barium-zirconates in the temperature range of 673-1273 K using deuterium (D2) and heavy water (D2O). Specimens were prepared with conventional powder metallurgy: the powder of three zirconates, BaZr0.9Y0.1O3-a (BZY), BaZr0.955Y0.03Co0.015O3-a (BZYC), and CaZr0.9In0.1O2.95 (CZI) was pressed into discs and fired in the air at 1873 K for 20 h. The densities of the sintered BZY, BZYC, and CZI specimens were 98 percent, 99.7 percent, and 99.5 percent of the theoretical densities respectively. XRD, SEM, and EDX were performed for the structural and morphological analysis of the sintered samples. From TDS measurement, a similar trend of temperature-dependent hydrogen solubility was obtained for all samples compared to the tritium imaging plate (TIP) methods literature data of HT- and DTO-exposed samples. To compare the experimental results of the deuterium desorption profile derived by TDS analysis, the simulation code of the tritium migration analysis program, version 4 (TMAP4) was employed.

Comparison of Hydrogen Embrittlement Susceptibility of Different Types of Advanced High-Strength Steels.

This study investigated the hydrogen embrittlement (HE) characteristics of advanced high-strength steels (AHSSs). Two different types of AHSSs with a tensile strength of 1.2 GPa were investigated. Slow strain rate tests (SSRTs) were performed under various applied potentials (Eapp) to identify the mechanism with the greatest effect on the embrittlement of the specimens. The SSRT results revealed that, as the Eapp increased, the elongation tended to increase, even when a potential exceeding the corrosion potential was applied. Both types of AHSSs exhibited embrittled fracture behavior that was dominated by HE. The fractured SSRT specimens were subjected to a thermal desorption spectroscopy analysis, revealing that diffusible hydrogen was trapped mainly at the grain boundaries and dislocations (i.e., reversible hydrogen-trapping sites). The micro-analysis results revealed that the poor HE resistance of the specimens was attributed to the more reversible hydrogen-trapping sites.

Crystal structure change in multilayer GeH flakes by hydrogen desorption under ultrahigh vacuum environments

To confirm the feasibility of a theoretically proposed method of forming free-standing germanene [Araidai et al., J. Appl. Phys. 128, 125301 (2020).], we experimentally investigated the hydrogen desorption properties of hydrogen-terminated germanane (GeH) flakes. Thermal desorption spectroscopy analysis revealed that hydrogen desorption occurred during heating under an ultrahigh vacuum environment corresponding to a mass loss of 1.0 wt%. Moreover, we have found that using an ultrahigh vacuum, ambient and short-time annealing for hydrogen desorption is a key to sustain the crystal structures.

Analysis of hydrogen trapping behaviour in plastically deformed quenching and partitioning steel in relation to microstructure evolution by phase transformation

The relationship between plastic deformation and hydrogen transport behaviour in the quenching and partitioning (Q&P) steel is studied. The evolution of microstructure after different levels of plastic deformation is characterized using the electron backscatter diffraction (EBSD) and X-ray diffraction technique. Also, the hydrogen diffusion and trapping of the plastically deformed Q&P steel are investigated using the hydrogen permeation electrochemical method and thermal desorption spectroscopy (TDS) on pre-strained specimens up to 14% engineering strain. The major findings through the experimental approach can be summarized as follows: (1) retained austenite fraction in Q&P steel decreased after plastic deformation; (2) the geometrically necessary dislocation (GND) density measured by KAM analysis increased; (3) hydrogen diffusivity decreased, while solubility increased as the plastic deformation increased. The increase in hydrogen trapping in the Q&P steel with plastic deformation can be attributed to the enhanced hydrogen trapping environment by increased dislocation density in ferrite and martensite transformed from metastable austenitic phase. The TDS analysis could support the hydrogen-trapping characteristics of Q&P steel, in which two major peaks were measured in different temperature ranges. Moreover, the EBSD observation and scanning transmission electron microscope (STEM) using transmission Kikuchi diffraction (TKD) analysis provided good correlation with the result of TDS analysis.

Comparative Studies of Hydrogen Dissolution and Release Behavior in Zirconate Oxides by TDS and TMAP4 Analysis

Proton-conducting oxides are potential materials for electrochemical devices such as fuel cells, hydrogen pumps, hydrogen sensors, and the tritium purification and recovery system in nuclear fusion reactors. The hydrogen concentration in oxide materials is important, but its precise measurement is difficult. In this study, thermal desorption spectroscopy (TDS) was used to investigate hydrogen dissolution and release behavior in proton-conducting oxides, yttrium (Y), and cobalt (Co) doped barium-zirconates in the temperature range of 673-1273 K using deuterium (D2) and heavy water (D2O). Specimens were prepared with conventional powder metallurgy: the powder of three zirconates, BaZr0.9Y0.1O3-a (BZY), BaZr0.955Y0.03Co0.015O3-a (BZYC), and CaZr0.9In0.1O2.95 (CZI) was pressed into discs and fired in the air at 1873 K for 20 h. The densities of the sintered BZY, BZYC, and CZI specimens were 98 percent, 99.7 percent, and 99.5 percent of the theoretical densities respectively. XRD, SEM, and EDX were performed for the structural and morphological analysis of the sintered samples. From TDS measurement, a similar trend of temperature-dependent hydrogen solubility was obtained for all samples compared to the tritium imaging plate (TIP) methods literature data of HT- and DTO-exposed samples. To compare the experimental results of the deuterium desorption profile derived by TDS analysis, the simulation code of the tritium migration analysis program, version 4 (TMAP4) was employed.

Hydrogen Absorption and Desorption Behavior on Aluminum-Coated Hot-Stamped Boron Steel during Hot Press Forming and Automotive Manufacturing Processes.

Our study mainly focused on diffusible hydrogen in aluminum–silicon-coated hot-stamped boron steel during a hot press forming process and in pre-treatment sequential lines of the automotive manufacturing process using a thermal desorption spectroscopy (TDS) technique. First, in the hot stamping procedure, as the soaking time increased in the heating furnace at a specific dew point when austenitizing, a high concentration of diffusible hydrogen was absorbed into the hot-stamped boron steel. Based on the TDS analysis of hydrogen absorbed from hot stamping, the activation energy value of hydrogen trapping in 1.8 GPa grade steel is lower than that of 1.5 GPa grade steel. This means that diffusible hydrogen can be more easily diffused into defective sites of the microstructure at a higher level of the tensile strength grade. Second, in sequential pre-treatment lines of the automotive manufacturing process, additional hydrogen did not flow into the surface, and an electro-deposition process, including a baking procedure, was effective in removing diffusible hydrogen, which was similar to the residual hydrogen of the as-received state (i.e., initial cold rolled blank). Based on these results, the hydrogen absorption was facilitated during hot press forming, but the hydrogen was sequentially desorbed during automotive sequential lines on aluminum-coated hot-stamped steel parts.

Deuterium retention in MeV ion-irradiated beryllium

Beryllium , as the material of choice for the ITER first wall, will be subject to high energy neutrons during the operation of the fusion device. Such irradiation will create displacement damage in the crystal lattice , which is known to influence hydrogen isotope retention, e.g. in iron and tungsten . In our study, we irradiated beryllium samples with high-energy oxygen ions up to various dpa levels (0.01 dpa, 0.1 dpa, and 1 dpa) and subsequently exposed the samples to deuterium plasma at 370 K and 573 K. The amount of retained deuterium was measured by thermal desorption spectroscopy and nuclear reaction analysis and was found to decrease by about 18% in the samples damaged up to 0.1 dpa compared to the undamaged ones. Further damaging up to 1 dpa did not show any additional effects on deuterium retention. Transmission electron microscopy was used to check for the existence of bubbles after plasma exposure.