Nb Material Research Articles

Study on the interstitial oxygen diffusion to understand the reduction of cryogenic RF loss for the superconducting radio-frequency niobium cavities

Abstract Medium-temperature baking (Mid-T baking) is an innovative method employed to enhance the unloaded quality factor Q0 of superconducting radio-frequency (SRF) niobium (Nb) cavities at cryogenic temperatures. This study presents an interstitial oxygen diffusion model based on the decomposition of the natural oxide to clarify the improved performance of the Nb cavities after undergoing Mid-T baking. Additionally, the correlation between the interstitial oxygen within the RF penetration depth and the surface resistance of the Nb cavities has been explored. The parameter for the oxide decomposition was determined using in-situ X-ray photoelectron spectroscopy (XPS), where the thickness of the oxide/carbide layer was calculated from the peak fitting of Nb 3d spectra and the attenuation law of the photoelectron beam. The interstitial oxygen diffusion model, validated by the semi-quantitative distribution along the depth determined by Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS), quantifies the oxygen atomic concentration within the RF penetration depth in Mid-T baked Nb material. In the baking temperature range of 300~400 ℃, the calculated oxygen concentration from the interstitial oxygen diffusion model demonstrates a more pronounced dependence on the baking temperature than the baking time. This suggests that more precise control of the interstitial oxygen concentration can be achieved by adjusting the baking temperature. Furthermore, it has been observed that maintaining a uniform and moderate oxygen concentration throughout the depth is essential for optimal BCS resistance. This study paves the way for more efficient processing optimization and enhancing understanding of the mechanism behind RF loss in Nb cavities.

Structural Reliability of pressure tube of a PHWR with volumetric flaws

The volumetric flaws can get generated in the pressure tubes (PT) of PHWR (made of Zr-2.5Nb material) during the operation of the reactor. The PT material has hydrogen present during the fabrication. Additionally, the zirconium material has a tendency to pick up hydrogen from the surrounding environment and can cause initiation of a crack through delayed hydride cracking (DHC) mechanism. This crack can grow due to the DHC and has the potential to cause leakage or break of the PT. The crack formation occurs only when a set of conditions are met. The model for the crack initiation ahead of the tip of a volumetric flaws is prescribed by the CSA Standard N285.8-15. The formation of the crack is dependent of the geometry of PT, geometry of the flaw (length, depth and root radius), applied loading (due to internal pressure, residual stresses), hydrogen concentration in the material and the material tensile and fracture properties. Most of these parameters are well defined. However, some of them like flaw geometry and material properties are not known with certainty. The structural reliability based methods quantify the uncertainty using probability distributions and present results in form of probability estimates. In this work, the probability of initiation of DHC ahead of a volumetric flaw and its subsequent growth is reported. Monte Carlo based simulation method along with variance reduction techniques is used to predict the probability. This study is useful to establish the Leak-Before-Break behaviour of the PT.

Enabling Jet-Electrochemical Discharge Machining on Niobium-Like Passivating Metal and the Single Step Fabrication of Coated Microstructures

Analogous to difficult-to-cut materials in mechanical machining, Niobium (Nb) is a difficult-to-dissolve metal by electrochemical machining (ECM) due to its prone-to-passivation nature. Jet-electrochemical discharge machining (Jet-ECDM), which uses anodic discharge rather than the cathodic discharge as in traditional ECDM, has been previously demonstrated as an efficient method for machining inert semiconductors like Si, 4H-SiC. However, applying Jet-ECDM on Nb-like passivating metal is very challenging because plasma electrolytic oxidation (PEO) is very prone to occur in the machining area due to anodic discharges, forming an insoluble, highly stable oxide coating that prevents material removal. This study reveals the principles of overcoming PEO to enable Jet-ECDM on metals. The findings show that the discharge intensity, affected by the electric field and pulse frequency, is decisive in achieving Nb material removal. The electrolyte chemistry significantly influences material removal fashions, depending on the electrolyte’s chemical activity. NaOH is the preferred choice for higher removal efficiency (maximum 1.92 mm min−1) and machining localization, while NaCl ensures better surface quality (Sa 99.4 nm). Moreover, the Jet-ECDM generated microstructure surface presents a thin layer of PEO coatings (<1 μm). This demonstrates the high potential of Jet-ECDM technology for efficient fabrication of coated microstructures in a single-step process.

Evaluation of predictive correlation between flux expulsion and grain growth for superconducting radio frequency cavities

Abstract A series of experiments were carried out in an effort to develop a simple method for predicting the magnetic flux expulsion behavior of high purity niobium used to fabricate superconducting radio frequency (SRF) cavities. Using conventional metallographic characterizations in conjunction with high spatial resolution electron backscattered diffraction-orientation imaging microscopy, we find that the flux expulsion behavior of 1.3 GHz single cell SRF Nb cavities is significantly associated with the grain growth of the Nb material during heat treatment. Most of the Nb grains rapidly grew during 900 °C heat treatment, and were likely full-recrystallized with 1000 °C HT. When compared to the magnetic flux expulsion ratio (B sc/B nc) at ΔT = 5 K, the flux expulsion efficiency of the cavities increases with the increase of grain size. Most interestingly, 900 °C HT shows a roughly linear trend that suggests that this criterion could be used to predict the appropriate heat treatment temperature for sufficient flux expulsion behavior in SRF-grade Nb. This result can be used to see if flux expulsion can be predicted by examining the materials coming from Nb vendors, prior to cavity fabrication.

Doping with Niobium Nanoparticles as an Approach to Increase the Power Conversion Efficiency of P3HT:PCBM Polymer Solar Cells.

Metal additive processing in polymer: fullerene bulk heterojunction systems is recognized as a viable way for improving polymer photovoltage performance. In this study, the effect of niobium (Nb) metal nanoparticles at concentrations of 2, 4, 6, and 8 mg/mL on poly(3-hexylthiophene-2,5-diyl) (P3HT)-6,6]-phenyl C61-butyric acid methyl ester (PCBM) blends was analyzed. The effect of Nb volume concentration on polymer crystallinity, optical properties, and surface structure of P3HT and PCBM, as well as the enhancement of the performance of P3HT:PC61BM solar cells, are investigated. Absorption of the P3HT:PC61BM mix is seen to have a high intensity and a red shift at 500 nm. The reduction in PL intensity with increasing Nb doping concentrations indicates an increase in PL quenching, suggesting that the domain size of P3HT or conjugation length increases. With a high Nb concentration, crystallinity, material composition, surface roughness, and phase separation are enhanced. Nb enhances PCBM's solubility in P3HT and decreases the size of amorphous P3HT domains. Based on the J-V characteristics and the optoelectronic study of the thin films, the improvement results from a decreased recombination current, changes in morphology and crystallinity, and an increase in the effective exciton lifespan. At high doping concentrations of Nb nanoparticles, the development of the short-circuit current (JSC) is associated with alterations in the crystalline structure of P3HT. The highest-performing glass/ITO/PEDOT:PSS/P3HT:PCBM:Nb/MoO3/Au structures have short-circuit current densities (JSC) of 16.86 mA/cm2, open-circuit voltages (VOC) of 466 mV, fill factors (FF) of 65.73%, and power conversion efficiency (µ) of 5.16%.

Cryogenic and hybrid induction-assisted machining strategies as alternatives for conventional machining of refractory tungsten and niobium

Tungsten (W) and niobium (Nb) belong to the refractory metal group and are used as alloying elements in steels and superalloys for high demand products. These metals are also used in a high purity single-phase state for products within nuclear, space, military and research facilities.In the current study, tool wear development and surface quality at different cutting conditions have been evaluated when machining high purity W 99.95% and Nb 99.7% in longitudinal turning. Cryogenic LN2 cooling and hybrid induction-assisted machining strategies were applied in order to alter W and Nb material state with respect to the ductile-to-brittle transformation temperature, and thus to attempt controlling their machinability. These advanced machining strategies were benchmarked against the more conventional machining solutions of dry, flood and high pressure cooling.It was found that the use of LN2 cooling demonstrated the best result in terms of tool life when machining W followed by induction-assisted heating, dry and flood. All machining strategies provided similar surface quality which is related to strong build-up edge formation and respective surface alteration. When machining Nb, high pressure coolant results in best performance in terms of tool life and surface quality, then followed by flood and cryogenic strategies. Overall, substantial improvement of surface quality (Ra = 0.4–0.6 μm) was observed for high cutting speeds vc ≥ 225 m/min.

High-temperature treatments of niobium under high vacuum, dilute air- and nitrogen-atmospheres as investigated by in situ X-ray absorption spectroscopy.

Niobium metal foils were heat-treated at 900°C under different conditions and in situ investigated with time-resolved X-ray absorption fine-structure (EXAFS and XANES) measurements. The present study aims to mimic the conditions usually applied for heat treatments of Nb materials used for superconducting radiofrequency cavities, in order to better understand the evolving processes during vacuum annealing as well as for heat treatments in controlled dilute gases. Annealing in vacuum in a commercially available cell showed a substantial amount of oxidation, so that a designated new cell was designed and realized, allowing treatments under clean high-vacuum conditions as well as under well controllable gas atmospheres. The experiments performed under vacuum demonstrated that the original structure of the Nb foils is preserved, while a detailed evaluation of the X-ray absorption fine-structure data acquired during treatments in dilute air atmospheres (10-5 mbar to 10-3 mbar) revealed a linear oxidation with the time of the treatment, and an oxidation rate proportional to the oxygen (air) pressure. The structure of the oxide appears to be very similar to that of polycrystalline NbO. The cell also permits controlled exposures to other reactive gases at elevated temperatures; here the Nb foils were exposed to dilute nitrogen atmospheres after a pre-conditioning of the studied Nb material for one hour under high-vacuum conditions, in order to imitate typical conditions used for nitrogen doping of cavity materials. Clear structural changes induced by the N2 exposure were found; however, no evidence for the formation of niobium nitride could be derived from the EXAFS and XANES experiments. The presented results establish the feasibility to study the structural changes of the Nb materials in situ during heat treatments in reactive gases with temporal resolution, which are important to better understand the underlaying mechanisms and the dynamics of phase formation during those heat treatments in more detail.

Prevalence and spectrum of chromosome abnormalities among spontaneous and induced early reproductive losses: 2020 miscarriages and 1572 medical abortions

This article presents the data of a comparative analysis of 9 large studies of non-developing pregnancies (NB) karyotype, published after 2000, as well as results of our own study of NB and medical abortion (MA), performed in the first trimester of pregnancy.Objective of the study: to assess the prevalence and structure of chromosomal abnormalities (CA) among spontaneous and induced reproductive losses in the first trimester of pregnancy.Materials and methods. From 1997 to 2019 karyotyping of concept products was carried out for NB (n = 2020) in terms of 5–13 weeks, obtained from women from 7 regions of the South-Eastern and Central regions of Ukraine, and MA (n = 1572) performed in the first trimester of pregnancy.Results. The efficiency of NB material karyotyping was 94%. Chromosomal pathology (CP) was 56.5% in NB material and 5.4% in MA material; autosomal trisomies – 51% of all CP among NB and 48.2% of all CP among MA; triploidy – 17.8% and 15.3% in the NB and MA groups, respectively; tetraploidy – 8.67% and 12.9%; monosomy X – 12.9% and 10.6%; restructuring – 5.5% and 10.6%; multiple trisomies – 3.2% and 3.5%, that is consistent with the data of other studies.In this study authors noted a significant predominance of 15, 16, 22 chromosomes trisomy over 13, 18, 21 chromosomes trisomy, as well as a large proportion of diandroid triploidies in comparison with other studies. Differences in the CA structure in anembryonic and NB with an embryo presence were established – multiple predominance of tetraploidies and structural rearrangements in anembryony and 15 chromosome trisomy, as well as X monosomy in an embryo presence. An association of mother's young age with a higher incidence of triploidies among NB was noted.Conclusions. The absolute majority of CA among NB and MA occurs sporadically, with exception of some structural rearrangements (robertsonian and reciprocal translocations). Our outcome analysis showed that standard karyotyping is still the first-line choice for examining the products of the concept of early pregnancy losses.

Fine Grain Resistance of Steel 20NiMoCr6-5+Nb (Material No. 1.6757) during Case Hardening depending on Cold Massive Forming∗

Abstract Cold massive forming of steel has been used for over 100 years to reduce mechanical finishing for cost reasons. A systematic investigation regarding the austenitic grain coarsening in the following heat treatment steps during the application treatment of e. g. gear steels could not be found, only indications of sporadic qualitative failures. The material 20NiMoCr6-5+Nb for gear shafts was subjected to a simulating treatment for the investigation of cold massive forming. No significant coarse grain growth was observed. Because the degree of cold massive forming at the individual shaft sections was not known, oblique samples were taken from the same bar steel lot, with which degrees of forming could be carried out steplessly from ∊ = 0 to 50 % on a press. After simulation of a high temperature carburization from 990 °C to 1050 °C, no significant coarse grain growth could be observed, only a uniform increase of the grain size index G with increasing temperature at the same holding time. In order to gain further knowledge in the field of modern manufacturing processes on the subject, newly available computer programs should to be used to simulate the production of components from case hardened steels from steel production to the ready to install part and to identify weak points.

A synchrotron X-ray diffraction study of strain and microstrain distributions in α-Zr caused by hydride precipitation

A thin zirconium hydride layer was deposited electrolytically on a hot-rolled and annealed Zr-2.5 wt.% Nb material. Changes in the α-Zr phase associated with the hydride precipitation were studied by synchrotron X-ray diffraction. Strain variations and the dislocation density in the α-Zr matrix were estimated from changes in diffraction peak positions and using X-ray Line Profile Analysis, respectively. It was shown that the dislocation density increased measurably in the α-Zr matrix due to the precipitation of the hydrides which corroborates previous transmission electron microscopy (TEM) observations indicating that the α-Zr accommodates some of the volume misfit by plastic deformation. The probable strain profile in the Zr-H system as a function of tested layer thickness is discussed.

Purification of Selective Laser Melting Additive Manufactured Niobium for Superconducting RF-Applications Transactions on Applied Superconductivity

Superconducting radio frequency (SRF)-cavities in the field of particle accelerators are mostly manufactured from bulk or sheet niobium (Nb). Complex shapes of SRF-components like high order mode-couplers or cavities working at high fields are high in cost and lead-time. The fabrication of these parts via additive manufacturing promises a more effective production and higher flexibility in geometries. At CERN, additive manufacturing with pure Nb by selective laser melting (SLM) is under development for future particle accelerator components. In comparison with conventionally produced Nb SRF-components, made of highly pure Nb, the SLM-manufactured Nb material contains considerable impurities due to raw material processing and the SLM-process conditions itself. Contaminations with light elements, such as oxygen and nitrogen, introduced into the material's structure by the powder and the SLM process, contribute to an important lowering of the residual resistance ratio (RRR). In order to increase the RRR-values for conventionally manufactured SRF-cavities, titanium (Ti) gettering-heat treatments were investigated since the 1980s. This paper introduces the first representative Nb-material realized at CERN by additive manufacturing by SLM and the current studies on the post-treatment of sample material by vacuum firing and Ti-gettering-heat treatments. The samples are analyzed by mass spectroscopy and RRR-measurements in correlation with different process parameters. First trials with Ti-gettering heat treatments demonstrate an increase in the RRR from 7 to above 100, whereas the oxygen content could be reduced from 600 to 17 ppm. These results show that a purification post-treatment of SLM-manufactured Nb-components is feasible and pave the way for functioning SRF-components made by additive manufacturing.

Influence of material parameters on the performance of niobium-based superconducting radiofrequency cavities

A detailed thermal analysis of a niobium (Nb)-based superconducting radiofrequency (SRF) cavity in a liquid helium bath is presented, by taking into account the temperature and magnetic field dependence of surface resistance and thermal conductivity in the superconducting state of the starting Nb material (for SRF cavity fabrication) with different impurity levels. The drop in SRF cavity quality factor ( $$Q_{0}$$ ) in the high acceleration gradient regime (before the ultimate breakdown of the SRF cavity) is studied in detail. It is argued that the high-field $$Q_0$$ -drop in SRF cavity is considerably influenced by the intrinsic material parameters such as electrical conductivity and thermal diffusivity. The detailed analysis reveals that the current specification on the purity of Nb material for SRF cavity fabrication is somewhat overspecified, as also inferred by the experimental work reported by some of the laboratories in the recent past. In line with these encouraging experimental results, in this paper, based on a rigorous calculation, we show that the Nb material with relatively low purity can very well serve the purpose for the accelerators dedicated for spallation neutron source (SNS) or accelerator-driven subcritical system (ADSS) applications, where the required accelerating gradient is typically up to $$20~\hbox {MV m}^{-1}$$ . This information will have important implication towards the cost reduction of superconducting technology-based particle accelerators for various applications. We think this theoretical work will be complementary to the experimental efforts performed in various laboratories at different corners of the globe.

Development of Niobium Microalloyed Steel for Railway Wheel with Pearlitic Bainitic Microstructure

Heavy haul transportation (load over 30 tons/axle), as well as the axle load, has been more and more used in Brazil and worldwide. The stress generated in the wheel-rail contact with loads up to 30 tons/axle is around 760 MPa, which causes premature wear and cracks of conventional wheels (AAR (Association of American Railroads) class C). Microalloyed wheels are fundamental on heavy haul transport, whose main function is to combine high hardness, ductility, and yield strength of the material in order to prevent shelling. The main purpose of this research is to develop a new microalloyed wheel steel with niobium addition that meets all the requirements of the AAR class D material with mixed microstructure composed of pearlite and bainite. The 0.71C/0.020Nb steel developed in this study (Nb material) for railroad achieved the standards required for AAR class D in all mechanical properties, with fracture toughness higher than the usual vanadium microalloyed steel used in comparison. The Continuous Cooling Transformation (CCT) diagram showed the presence of bainite even at very low cooling rate, in the range between 0.3 - 2 °C/s. These cooling rates to form bainite are much lower than those observed in other steels with similar composition.

(Invited) Study on Electro-Polishing of Nb Surface By Periodic Reverse Current Method with Sodium Hydroxide Solution for Particle Accelerator Application

Superconducting Radio-Frequency (SRF) cavities are used to accelerate particles in particle accelerators. In this application, the cavity is made of niobium (Nb) material and the inner surface of cavity should be polished so as to obtain the high performance of particle accelerator. The Electro-Polishing (EP) process is one of the best methods to polish the inner-surface of Nb cavity where the electrolyte is the mixture of sulfuric and hydrofluoric acids. However, this EP electrolyte is very dangerous in the operation and thus the operators need rigorous protection. Furthermore, all parts of instrument for the EP process must be made of high density polyethylene or fluorocarbon resin because the corrosion of metal occurs by hydrofluoric acid. These are the reasons why the cost of EP process becomes very expensive. In addition, the EP process produces sulfur compound on the Nb surface as a by-product. This sulfur compound can be the sources of field-emission on the inner surface of cavity and degrades the accelerating performance. In this article, we report a novel EP method using periodic reverse current and sodium hydroxide solution. The reaction produces no sulfur content and the instrument is less expensive because it is made of usual plastic material. As the result of experiments with Nb-coupon samples, we found that the surface roughness is equivalent to the conventional EP method. And some experiments with a Nb single-cell cavity will be reported.

Synthesis and characterization of Ti-27.5Nb alloy made by CLAD® additive manufacturing process for biomedical applications

Biocompatible beta-titanium alloys such as Ti-27.5(at.%)Nb are good candidates for implantology and arthroplasty applications as their particular mechanical properties, including low Young's modulus, could significantly reduce the stress-shielding phenomenon usually occurring after surgery. The CLAD® process is a powder blown additive manufacturing process that allows the manufacture of patient specific (i.e. custom) implants. Thus, the use of Ti-27.5(at.%)Nb alloy formed by CLAD® process for biomedical applications as a mean to increase cytocompatibility and mechanical biocompatibility was investigated in this study. The microstructural properties of the CLAD-deposited alloy were studied with optical microscopy and electron back-scattered diffraction (EBSD) analysis. The conservation of the mechanical properties of the Ti-27.5Nb material after the transformation steps (ingot-powder atomisation-CLAD) were verified with tensile tests and appear to remain close to those of reference material. Cytocompatibility of the material and subsequent cell viability tests showed that no cytotoxic elements are released in the medium and that viable cells proliferated well.

Possible influence of surface oxides on the optical response of high-purity niobium material used in the fabrication of superconducting radio frequency cavity

We have investigated the possible influence of surface oxides on the optical properties of a high-purity niobium (Nb) material for fabrication of superconducting radio frequency (SCRF) cavities. Various peaks in the infrared region were identified using Fourier transform infrared and Raman spectroscopy. Optical response functions such as complex refractive index, dielectric and conductivity of niobium were compared with the existing results on oxides free Nb and Cu. It was observed that the presence of a mixture of niobium-oxides, and probably near other surface impurities, appreciably influence the conducting properties of the material causing deviation from the typical metallic characteristics. In this way, the key result of this work is the observation, identification of vibrational modes of some of surface complexes and study of its influences on the optical responses of materials. This method of spectroscopic investigation will help in understanding the origin of degradation of performance of SCRF cavities.

Effect of Hot Isostatic Pressing on the Microstructure and Propertiesof Kinetic Sprayed Nb Coating Material

Niobium is one of the most important and rarest metals, and is used in the electronic and energy industries. However, it`s extremely high melting point and oxygen affinity limits the manufacture of Nb coating materials. Here, a Nb coating material is manufactured using a kinetic spray process followed by hot isotactic pressing to improve its properties. OM (optical microscope), XRD (X-ray diffraction), SEM (scanning electron microscopy), and Vickers hardness and EPMA (electron probe micro analyzer) tests are employed to investigate the macroscopic properties of the manufactured Nb materials. The powder used to manufacture the material has angular-shaped particles with an average particle size of . The porosity and hardness of the manufactured Nb material are 0.18% and 221 Hv, respectively. Additional HIP is applied to the manufactured Nb material for 4 h under an Ar atmosphere after which the porosity decreases to 0.08% and the hardness increases to 253 Hv. Phase analysis after the HIP shows the presence of only pure Nb. The study also discusses the possibility of using the manufactured Nb material as a sputtering target.

Measurement of mechanical properties of a reactor operated Zr–2.5Nb pressure tube using an in situ cyclic ball indentation system

Periodic measurement of mechanical properties of pressure tubes of Indian Pressurised Heavy Water Reactors is required for assessment of their fitness for continued operation. Removal of pressure tube from the core for preparation of specimens to test for mechanical properties in laboratories consumes large amounts of radiation and hence is to be avoided as far as possible. In the field of in situ estimation of properties of materials, cyclic ball indentation is an emerging technique. Presently, commercial systems are available for doing indentation test either on outside surface of a component at site or on a test piece in a laboratory. However, these systems cannot be used inside a pressure tube for carrying out ball indentation trials under in situ condition. Considering this, a remotely operable hydraulic In situProperty Measurement System (IProMS) based on cyclic ball indentation technique has been designed and developed in house. The tool head of IProMS can be located inside a pressure tube at any axial location under in situ condition and the properties can be estimated from an analysis of the data on load and depth of indentation, recorded during the test. In order to qualify the system, a number of experimental trials have been conducted on spool pieces and specimens prepared from Zr–2.5Nb pressure tube having different mechanical properties. Based on the encouraging results obtained from the qualification trials, IProMS has been used inside a reactor operated pressure tube which has been removed from Kakrapar Atomic Power Station-2 after 12.76 Full Power Years of operation for post irradiation examination studies at Bhabha Atomic Research Centre. This paper highlights the basic theory of measurement, results from the qualification trials on Zr–2.5Nb material having different mechanical properties and reactor operated irradiated pressure tube.

Helminth-conditioned dendritic cells prime CD4+ T cells to IL4 production in vivo (IRC5P.469)

Abstract Dendritic cells are critical for the initiation of immune responses, however, their role in priming IL4-producing Th2 cells is controversial and remains an area of intense investigation. We found that after skin injection of the nematode parasite Nippostrongylus brasiliensis (Nb), a strong inducer of Th2 responses, Nb material is taken up by a population of dermal dendritic cells in lymph node, and that this population is necessary and sufficient for IL4 priming. Blocking the migration of dermal dendritic cells to the lymph node also prevented the priming of IL4-producing cells, and chicken ovalbumin (OVA)-loaded dDC from Nb-treated mice were sufficient to sensitize OVA-specific CD4+ T cells to IL4 production in vivo. Nb-loaded dermal dendritic cells were CD11b+, CD326neg, CD103neg, PDL2hi and IRF4+, and modestly upregulated expression of OX40L. However, OX40L and TSLP were not required for Th2 priming. Thus, our data suggest that the appropriate stimuli can induce DC to express the unique signals that direct CD4+ T cells to Th2 differentiation.

Multi-field modelling of hydride forming metals Part II: Application to fracture

In Part I of the present article, we formulated a continuum-based computational model for stress- and temperature-directed diffusion of hydrogen in metals that form brittle binary hydrides, such as Zr and Ti alloys. Among the space–time dependent parameters calculated by the model are the volume fraction and the mean orientation of hydride precipitates. These parameters are of importance for quantifying the embrittlement of hydrided materials. In this second part of the work, we use measured data for the strength and toughness of hydrided Zr alloys to correlate the local fracture properties of the two-phase (metal+hydride) material to the aforementioned parameters. The local fracture properties are used as space–time dependent input to a cohesive zone type submodel for fracture, which is fully integrated with the hydrogen transport model from Part I. The complete model is validated against fracture tests on hydrogen-charged Zr–2.5%Nb, a material used in nuclear reactor pressure tubes. More precisely, we study local embrittlement and crack initiation at a blunt and moderately stressed notch, resulting from gradual accumulation of hydrides at the notch during temperature cycling. We also simulate tests on crack initiation and growth by delayed hydride cracking, a subcritical crack growth mechanism with a complex temperature dependence. From the results of the simulations, we conclude that the model reproduces many observed features related to initiation and propagation of hydride induced cracks in the Zr–2.5%Nb material. In particular, it has the capacity to reproduce effects of the material’s temperature history on the fracture behaviour, which is important for many practical applications.