Difference In Corrosion Behavior Research Articles

A study of a non‐conventional evaluation of results from salt spray test of aluminum High Pressure Die Casting alloys for automotive components

Aim of the present work was to investigate in a non‐conventional way the results of aluminum castings salt spray tests. These experiments were engineered in order to obtain a quantitative measurement of the corrosion rate, instead of the qualitative visual analysis usually employed in the traditional salt spray test. These tests were performed on aluminum EN AC‐46000, EN AC‐44400, and EN AC‐43500 samples. A comparison was made with electrochemical tests on specimens and the traditional salt spray testing on a real dimension component. The results showed a good reliability of the new method that gave outputs in agreement with the electrochemical technique. The new concept of salt spray test data processing was able to detect very small differences in corrosion behavior of tested alloys, demonstrating higher precision and reliability in respect to the polarization technique. Such result was explained considering the adoption of specimen with larger area and longer time of exposure to the selected corrosive environment that reduce respectively the effect of uneven distribution of porosity and intermetallics in the samples, typical of aluminum castings, and the potential local and transient events related to these defects.

X-ray Radiography to Visualize the Rebar-Cementitious Matrix Interface and Judge the Delay in Corrosion through Self-Repair by Encapsulated Polyurethane

Corrosion of steel reinforcement is one of the most detrimental attack mechanisms for reinforced concrete structures. The presence of cracks, which are inextricably linked to reinforced concrete, accelerates this attack mechanism. The aim of this study is to heal cracks by an autonomous mechanism, which is triggered upon crack appearance. With an accelerated corrosion test on mortar samples with embedded reinforcement bars, it is shown that the presence of cracks indeed accelerates the onset and propagation of corrosion at the interface between the rebar and the cementitious matrix. Moreover, it is shown that crack healing in both the traditional, manual way and the proposed autonomous way, with an encapsulated one-component polyurethane, delays the onset and propagation of corrosion. The difference in corrosion behavior is proven by visual evaluation of the rebar surface and by X-ray radiographic analysis, which is proposed as a successful technique to evaluate the crack healing efficiency and more specifically the potential to delay corrosion.

Corrosion Monitoring of Reinforcing Bar in Concrete Under Different Corrosive Environments

Reinforced concrete structures have been widely used for social infrastructures because of their high strength. However, it currently has been passed over 50 years since many infrastructures constructed, and the deterioration in durability is a problem. The corrosion of reinforcing bars due to neutralization of concrete and adhesion of airborne sea salt, and the concrete cracking by corrosion products is considered as the main cause of deterioration. Therefore, in order to properly maintain and manage the infrastructure structure, it is necessary to understand the corrosion deterioration behavior of the reinforcing bars in the concrete. In this study, wet and dry cyclic corrosion test was conducted using concentric ring type electrodes of carbon steel covered with mortar. The difference in corrosion behavior of reinforcing bars due to covering thickness and corrosion test conditions was investigated by continuously measuring the impedance between two electrodes. Furthermore, the diffusion behavior of water and chloride ions in mortar part was observed, and the correlation with corrosion behavior was investigated The concentric ring type electrodes of carbon steel were used as the monitoring electrodes, and they were covered with the different thickness of mortar (hereinafter, the mortar electrode). The composition of the mortar was coarse aggregate: cement: water = 3: 1: 0.6. 10 kg/m3 NaCl was added to the mortar to accelerate corrosion. The covering thickness was set to 3, 10 mm. The corrosion test was carried out by wet and dry cycle, and the electrochemical impedance at two frequencies of 10 mHz and 10 kHz was continuously measured during the corrosion test. A core having a height of 50 mm and a diameter of 40 mm was prepared with the same composition of mortar. The prepared cores were immersed in 0.1 mol/L NaCl solution for several hours. The permeation state of water and chloride ion was investigated by water leakage test agent and fluorescent X - ray analysis. Changes in the corrosion rate of the mortar electrode prepared by underwater curing in the wet and dry cyclic corrosion process were continuously measured. Although there was some variation, corrosion rate decreased in the immersion process, regardless of the thickness of the mortar. The corrosion rate of the electrode with 3 mm mortar showed higher value than that with 10 mm mortar. The changes in corrosion rate and solution resistance in each cycle of corrosion test were examined. The solution resistance gradually decreases in the wet process, and the value showed a minimum in the drying process. This means that diffusion rate of the solution is slow in the mortar. Since the decrease in solution resistance corresponds to the increase in corrosion rate, it is considered that the increase in corrosion rate is due to wetting by the permeated solution. There was a large fluctuation in the electrode with 3 mm mortar, whereas the electrode with 10 mm mortar always showed a low solution resistance value regardless of process of the corrosion test. This difference in wetting environment can affect the change in corrosion rate and corrosion behavior.

Surface chemistry and corrosion behavior of Inconel 625 and 718 in subcritical, supercritical, and ultrasupercritical water

Corrosion behavior of Inconel 625 and 718 in subcritical, supercritical and ultrasupercritical water was studied as a function of temperature and time. The change in the chemistry of the as-received surface film on Inconel 625 and 718 after exposure to subcritical water at 325°C and supercritical water at 425°C and 527.5°C for 2h was studied. After exposure to 325°C subcritical water, the CrO42− based film formed; however minor quantities of NiFexCr2-xO4 spinel compounds were observed. The oxide film formed on both alloys when exposed to supercritical water at 425°C consisted of NiFexCr2-xO4 spinel. The surface films on both alloys were identified as NiFe2O4 when exposed to supercritical water at 527.5°C. To characterize the fully developed oxide layer, studies were conducted at test solution temperatures of 527.5 and 600°C. Samples were exposed to these temperatures for 24, 96, and 200h. Surface chemistry was analyzed using X-ray diffraction, as well as Raman and X-ray photoelectron spectroscopies. Inconel 718 exhibited greater mass gain than Inconel 625 for all temperatures and exposure times. The differences in corrosion behavior of the two alloys are attributed to the lower content of chromium and increased iron content of Inconel 718 as compared to Inconel 625.

Effects of simulated inflammation on the corrosion of 316L stainless steel

Stainless steel alloys, including 316L, find use in orthopaedics, commonly as fracture fixation devices. Invasive procedures involved in the placement of these devices will provoke a local inflammatory response that produces hydrogen peroxide (H2O2) and an acidic environment surrounding the implant. This study assessed the influence of a simulated inflammatory response on the corrosion of 316L stainless steel. Samples were immersed in an electrolyte representing either normal or inflammatory physiological conditions. After 24h of exposure, electrochemical impedance spectroscopy (EIS) and inductively coupled plasma mass spectroscopy (ICPMS) were used to evaluate differences in corrosion behavior and ion release induced by the inflammatory conditions. Scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDX) were used to evaluate surface morphology and corrosion products formed on the sample surface. Inflammatory conditions, involving the presence of H2O2 and an acidic pH, significantly alter the corrosion processes of 316L stainless steel, promoting aggressive and localized corrosion. It is demonstrated that particular consideration should be given to 316L stainless steel implants with crevice susceptible areas (ex. screw-head/plate interface), as those areas may have an increased probability of rapid and aggressive corrosion when exposed to inflammatory conditions.

Effect of substrate temperature and nitrogen concentration during sputtering on corrosion behaviour of AlN coatings

Aluminium nitride coatings were formed on stainless steel substrate by DC-reactive balanced magnetron sputtering at various nitrogen concentrations in the sputtering gas mixture, and different substrate temperatures. The electrochemical corrosion behaviour of the coatings obtained was studied in 0.5 M H2SO4. Continuous improvement in corrosion resistance of the coatings was observed with increasing coating deposition temperature up to 500 °C. The corrosion potential shifted from −0.66 VSCE at 100 °C to −0.33 VSCE at 500 °C. Accordingly, the corrosion current density decreased significantly with increase in the deposition temperature. However, no major difference in corrosion behaviour could be noticed for the coatings formed at various nitrogen concentrations.

In-Situ Corrosion Monitoring of Iron and Zinc in Atmospheric Environments

Traditionally, for evaluating corrosion resistance of materials used in atmospheric conditions, exposure tests in the actual environment and accelerated corrosion tests in the laboratory have been widely used. Till now, it has been very difficult to estimate in detail corrosion rate variations caused by the change of each environmental factor such as temperature, relative humidity, amount of airborne sea salt during the test periods. Also, it requires a long time period to evaluate the corrosivity in actual corrosive atmospheric environments. For these reasons, an in-situ corrosion monitoring technique is useful. Time variation of corrosion rate has been successfully monitored by using an electrical resistance corrosion sensor, which converts the increase of electrical resistance caused by metal consumption to corrosion loss. Additionally, a new accelerated corrosion test was authorized as ISO 16539 Method B on March 1, 2013. This test has good correlation with corrosion behavior in an actual corrosive atmospheric environment. In this study, the details of the corrosion rate of steel and zinc were evaluated by the accelerated corrosion test (ISO 16539 Method B) and atmospheric exposure test. In addition, the relation between corrosion rate and each environmental factor was analyzed. Two kinds of electrical resistance corrosion sensors, an Fe sensor (250 µm thick) and a Zn sensor (50 µm thick), were used. In the accelerated corrosion test (ISO16539-Method B), the corrosion depth as evaluated by the sensors displayed a good correlation with that of the exposure test samples. The variation in the corrosion rate could be evaluated by the sensors. And also, it was confirmed that the corrosion rate increased during the wet stage and decreased during the dry stage in both sensors. In exposure tests in Okinawa and Kawasaki, the variation of the corrosion rate due to the effects of changeable environmental conditions throughout the year could be evaluated by the sensors. Okinawa is seashore area at the s southern island in Japan, and Kawasaki is industrial area in Japan. The corrosion rate in Okinawa as evaluated by the Fe sensor was greater than that found in Kawasaki. However, the corrosion rate in Okinawa as evaluated by the Zn sensor was almost the same as that in Kawasaki. The corrosion sensors could clarify the difference in corrosion behavior between steel and zinc. Furthermore, the relationship between the corrosion rate and the environmental factors (temperature, relative humidity, amount of airborne sea salt, etc.) was analyzed. The corrosion rate of steel had a positive relation with temperature, relative humidity and airborne sea salt. The dependence of corrosion rate of zinc on environmental factors was also investigated. Comparison of corrosion behavior and its dependence of environmental factors between iron and zinc will be discussed.

Effect of heat treatment on hydrogen permeation behaviour of AISI 4135 steel under splash zone conditions

Effect of heat treatment on the hydrogen permeation behaviour of AISI 4135 steel was studied by electrochemical method under simulated splash zone conditions. The hydrogen permeation current reached maximum at dry stage and the amount of hydrogen permeated showing a maximum in sixth cycle. Moreover, it was found that the amount of hydrogen permeated through specimen with bainitic microstructure was lower than that in other specimens. The average value of charge transfer resistances for heat treated specimens A, B, C and D exhibit no significant differences under nature sea water film. Moreover, the heat treatments have no prominent impact on corrosion products from the X-ray diffraction (XRD) pattern and SEM analysis. Therefore, the differences in hydrogen permeation behaviours were mainly attributed to the microstructures of specimens other than the differences in corrosion behaviour.

Corrosion reliability of copper wirebond (CuWB) packages-Impact of voltage and corrosive ions from packaging materials

Reliability of electronic devices used in extreme and harsh conditions such as in automotive applications is often associated with prevention of corrosion at the interfaces of dissimilar interconnect metals and of metal (Al or Cu) bonding pads. Packaging materials, especially molding compounds, contain several ionic components and can uptake certain level of moisture to provide electrolytic conditions to initiate corrosion processes. Probability of occurrence of corrosion in devices with high voltage applications is of special interest as many analog devices operates at higher voltages and with new CuWB packages there is a higher susceptibility of corrosive failures. This paper examines the impact of voltage on the mold compound compatibility with CuWB packages up to 65 V. Bias HAST reliability evaluation of various mold compounds at different voltages will be described. Corrosion of bonding pad (Al) and at the Al-Cu intermetallic compound interface was observed in the presence of certain ions present in mold compounds. Even though current mold compounds are “green”, the allowable amounts of halide ions can far exceed the ppm limit to prevent CuWB corrosive failures. Bromide ions are known to be very corrosive to metals. Br ions are still present in some mold compounds. The impact of the Br ion on CuWB reliability will be described. Additive impact of Br ions in presence of Cl will be examined. Another corrosive component present in many mold compounds, sulfur compounds, also can be corrosive under certain reliability stress conditions. Difference in corrosion behavior of Cu and Pd –Cu wirebonded packages due to sulfur compounds will be presented. Corrosive impact of high levels of Cl on the Al pad corrosion leading thick aluminum oxide growth and reliability failures will be discussed.

Surface characteristics and corrosion properties of selective laser melted Co–Cr dental alloy after porcelain firing

ObjectiveWe examined the surface characteristics and corrosion properties of selective laser melted (SLM) cobalt–chromium (Co–Cr) dental alloys before and after porcelain-fused-to-metal (PFM) firing. MethodsSamples were manufactured utilizing SLM techniques and control specimens were fabricated using traditional casting methods. The microstructure and surface composition were examined using metallographic microscopy, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Corrosion properties were evaluated using electrochemical impedance spectroscopy. Student's t-test was used to evaluate differences in numerical results of electrochemical corrosion tests between SLM and cast specimens before or after PFM firing. The results of electrochemical corrosion tests of the SLM and cast samples before and after firing were analyzed using one-way ANOVA. ResultsAlthough PFM firing altered the microstructure of the SLM specimens, they still exhibited a compact and homogeneous structure, and XPS analysis indicated that there were no significant differences in the surface composition of the specimens after firing. In artificial saliva at pH 5, the Rp value of the SLM specimens was 6.21MΩcm−2 before firing and 2.84MΩcm−2 after firing, suggesting there was no significant difference in electrochemical corrosion properties (P>0.05). In artificial saliva at pH 2.5, the Rp value of the SLM group was 4.80MΩcm−2 before firing and 2.88MΩcm−2 after firing, again indicating no significant difference in electrochemical corrosion properties (P>0.05). At pH 2.5, there was a significant difference in corrosion behavior between the cast and SLM groups, with the Rp value of the cast group being 0.78MΩcm−2 vs. 2.88MΩcm−2 for the SLM group. SignificanceThe improved post-firing corrosion resistance of SLM specimens provides further support for their use in prosthodontic applications, as the oral environment may become temporarily acidic following meals.

Comment on “Electrochemical behavior of different structural states of the alloy Ti60Ni40” by S. Mathur et al. and related works

In the recent studies by Shubhra Mathur et al. [1–3], Ti60Ni40 alloys (metallic glasses) were investigated in terms of their corrosion behavior in dependence on ion beam irradiation [1] and in dependence on their crystalline state, i.e. crystalline, amorphous and nanocrystalline, [2] or “nanocrystalline I”, “nanocrystalline II” and “nanocrystalline III” [3]. Differences in corrosion behavior result in the formation of oxide films with different amounts of Ti0, Ti2+, Ti3+and Ti4+, as deduced from the analysis of the spectral line shapes of Ti-2p spectra and O-1s spectra in X-ray photoelectron spectroscopy (XPS). Unfortunately, the authors' analysis of data from photoemission does not meet the physics of photoemission, and therefore, some statements from Ref. [1–3] are not beyond any doubt.

Long-term Corrosion of Zircaloy-4 and Zircaloy-2 by Continuous Hydrogen Measurement under Repository Condition

ABSTRACTCorrosion behavior is a key issue for the waste disposal of irradiated metals, such as hulls and endpieces, and is considered to be a leaching source of radionuclides including C-14. However, little information about Zircaloy corrosion in anticorrosive conditions has been provided.In the present study, long-term corrosion tests of Zircaloy-4 and Zircaloy-2 were performed in assumed disposal conditions (dilute NaOH solution, pH 12.5, 303 K) by using the gas flow system for 1500 days. The corrosion rate, which was determined by measuring gaseous hydrogen and the hydrogen absorbed in Zircaloy, decreased with immersion time and was lower than the value of 2×10−2 μm/y used in performance assessment (1500-day values: 5.84×10−3 and 5.66×10−3 μm/y for Zircaloy-4, 1000-day values: 8.81×10−3 μm/y for Zircaloy-2). The difference in corrosion behavior between Zircaloy 4 and Zircaloy-2 was negligible. The average values of the hydrogen absorption ratios for Zircaloy-4 and Zircaloy-2 during corrosion were 91% and 94%, respectively.The hydrogen generation kinetics of both gas evolution and absorption into metal can be shown by a parabolic curve. This result indicates that the diffusion process controls the Zircaloy corrosion in the early corrosion stage of the present study, and that the thickness of the oxide film in this stage is limited to approximately 25 nm and may therefore be in the form of dense tetragonal zirconia.

Effects of pH and elevated glucose levels on the electrochemical behavior of dental implants.

Implant failure is more likely to occur in persons with medically compromising systemic conditions, such as diabetes related to high blood glucose levels and inflammatory diseases related to pH levels lower than those in healthy people. The aim of this study was to investigate the effects of lower pH level and simulated- hyperglycemia on implant corrosion as these effects are critical to biocompatibility and osseointegration. The electrochemical corrosion properties of titanium implants were studied in four different solutions: Ringer's physiological solution at pH = 7.0 and pH = 5.5 and Ringer's physiological solution containing 15 mM dextrose at pH = 7 and pH = 5.5. Corrosion behaviors of dental implants were determined by cyclic polarization test and electrochemical impedance spectroscopy. Surface alterations were studied using a scanning electron microscope. All test electrolytes led to apparent differences in corrosion behavior of the implants. The implants under conditions of test exhibited statistically significant increases in I(corr) from 0.2372 to 1.007 μAcm(-2), corrosion rates from 1.904 to 8.085 mpy, and a decrease in polarization resistances from 304 to 74 Ω. Implants in dextrose-containing solutions were more prone to corrosion than those in Ringer's solutions alone. Increasing the acidity also yielded greater corrosion rates for the dextrose-containing solutions and the solutions without dextrose.

The Effect of the Amorphous and Crystalline States on Preferential Corrosion of Hf from a Cu75Hf20Dy05 Alloy

Amorphous solid-solution Cu75Hf20Dy05, which undergoes devitrification without changing composition either locally or globally, was used to examine the effects of structural ordering on corrosion properties in the absence of any accompanying chemical partitioning. Melt spun amorphous Cu75Hf20Dy05 undergoes single-phase devitrification to a Cu51Hf14 phase. The difference in corrosion behavior between these two structures was explored in hydrofluoric acid solutions where preferential dissolution of hafnium occurred. Preferential Hf dissolution occurred more readily in the amorphous alloy compared with its crystalline counterpart. Remaining copper reorganized to form a face-centered cubic (fcc) nanostructure in both conditions, but this process occurred quickly in the amorphous state and more slowly in the crystalline variant. A uniform, nanoporous Cu sponge structure, with a pore diameter of approximately 10 nm, formed after dissolution in the amorphous state. A less uniform, nanoporous structure developed more slowly when occurring from the crystalline state. These differences were traced to the effects of ordering on both dissolution and surface diffusion.

Effect of microstructure evolution on corrosion of different crystal surfaces of AZ31 Mg alloy in a chloride containing solution

The crystallographic basal plane dominated rolling surface (RS) of AZ31 Mg alloy has higher corrosion resistance in a chloride containing solution than its prismatic plane dominated cross-section surface (CS). The microstructures of these two surfaces with different crystallographic orientations evolve at 450 °C, resulting in larger grains, less twins, and more Al 8Mn 5 particles. Among these changes, the precipitated Al 8Mn 5 intermetallic phase during heat-treatment is responsible for the reduced corrosion resistance of the RS and CS surfaces. The electrochemical galvanic effect of the intermetallic particles suppresses the influence of crystallographic orientation and leads to a diminished difference in corrosion behavior between the RS and CS surfaces.

Reaction behavior of slag and spinel in steel ladle castables

The difference in corrosion behavior between alumina-spinel and alumina-magnesia castables in a steel slag was investigated with emphasis on the composition of spinel phase. The spinel primarily-added to the alumina-spinel castable had the stoichiometric composition, whereas the spinel forming secondarily in the alumina-magnesia castable was in an alumina-rich composition. The model reaction between sintered spinel and slag revealed that the stoichiometric spinel was highly wettable to slag and the molten slag deeply penetrated into the sintered body. In contrast, the alumina-rich spinel was less wettable. It was found that the alumina-rich spinel changed into stoichiometric one at the interface between spinel and slag, and that an iron-alumina spinel formed following to dissolution of the excessive alumina into slag. The increase in alumina content seemed to increase the viscosity of the slag, leading to retardation of penetrative wetting of slag to the alumina-rich spinel.

Comparison of corrosion behaviour of zinc in NaCl and in NaOH solutions; Part II: Electrochemical analyses

Electrochemical impedance spectroscopy (EIS) is a powerful analysis technique which can provide a wealth of information about the corrosion reactions of pure zinc. Although a huge amount of potentially useful data can be generated using the EIS technique, these data need to be carefully interpreted. This is usually done using an ‘equivalent circuit’ which comprises an assembly of electrical circuit elements allowing to model the physicoelectric characteristics of the electrode/solution interface. Research on corrosion behaviour of pure zinc in 0.6 M NaCl and 0.5 M NaOH solution was carried out using the EIS technique. The relevant equivalent circuits (EC) are developed by fitting EIS data to build up a description of the influence of the corrosion layer formed on the top of pure zinc immersed in 0.6 M NaCl and 0.5 M NaOH solution. Before using EIS analysis, voltammetric studies (open circuit potential and anodic polarization) completed by scanning electron microscope observations were conducted. A difference in corrosion behaviour was relieved between the two corrosive media. In 0.5 M NaOH solution, the passivation of zinc was observed but not in 0.6 M NaCl solution.

Biocorrosion Behavior of Titanium Oxide/Butoxide-Coated Stainless Steel

Stainless steel coated with multilayers of Ti oxide/butoxide was prepared via a layer-by-layer sol-gel deposition process. The successful buildup of the Ti oxide/butoxide coatings was ascertained by X-ray photoelectron spectroscopy and static water contact angle measurements. The differences in corrosion behavior between the Ti oxide/butoxide-coated and the uncoated coupons in a simulated seawater-based modified Baar’s medium inoculated with Desulfovibrio desulfuricans under anaerobic conditions were investigated by electrochemical analyses, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy (EDX). Electrochemical analyses and SEM results revealed that the pristine, the hydroxylated, and the nitric acid-passivated coupons were all vulnerable to biocorrosion due to localized breakdown of the passive film under synergistic attack of Desulfovibrio desulfuricans and biogenic sulfide ions, leading to destructive pitting and crevice corrosion. However, the Ti oxide/butoxide-coated coupons exhibited desirable resistance in the biocorrosion environment and the coating remained relatively stable throughout the exposure period. EDX analysis revealed that the bioactive properties of the Ti oxide/butoxide coating arose from the concomitant deposition of calcium and phosphorous compounds. The increase in resistance of the Ti oxide/butoxide coatings with time was correlated with the increase in nucleation of calcium apatite in electrochemical studies.

A silane pre-treatment for improving corrosion resistance performances of emeraldine base-coated aluminium samples in neutral environment

An aluminium–magnesium alloy AA5182 substrate pre-treated with a 3-aminopropyl-triethoxysilane (APS)-based solution and coated with emeraldine base (EB) showed improved corrosion resistance to neutral salt spray test, compared to samples pre-treated with phosphoric acid-based solutions prior to the EB coating. Scanning electron microscopy (SEM) and energy dispersive X-ray spectrometry (EDX) characterisations of samples pre-treated with APS showed the presence of an uneven silane coating on the aluminium surface according to the surface microstructure. The potentiodynamic study performed on the EB-coated samples showed a noticeable reduction of corrosion current of coupons pre-treated with APS, while no relevant difference in corrosion behaviour was observed between APS and phosphoric acid pre-treated samples prior to the EB coating. The coupling activity of APS between the AA5182 surface and EB coating at the most sensitive corrosion sites could be responsible of an improved adhesion of the EB coating at these points and could explain the observed improved corrosion resistance.

Zirconium alloys for supercritical water reactor applications: Challenges and possibilities

The corrosion behavior of model Zr-based alloys at 500 °C is assessed by long term (up to 400 days) corrosion testing in an effort to evaluate their potential for use in the supercritical water reactor and to assess the influence of alloying elements on corrosion behavior. The corrosion weight gains from such systematic testing are seen to be a factor of five higher than those measured at 360 °C but the protectiveness ranking of the alloys is similar. Detailed characterization of the oxide layers to rationalize the differences in corrosion behavior was performed using synchrotron radiation and systematic differences are observed in protective and non-protective oxides, especially near the oxide–metal interface. The overall corrosion rate of the best Zr-based alloys compared favorably with those of other alloys being considered for use in the supercritical water reactor.