Yuqing Niu

L-3 Communications · shantou university

The corrosion behavior of two cast Fe-xCr-5Si (x = 0, 5 at.%) alloys has been studied at 800°C in H2-CO2-H2S mixture. The addition of 5 at.% Cr improved the corrosion resistance of the Fe-5Si alloy by forming a protective scale of mixed Cr2O3 and SiO2 at the bottom of a non-uniform scale. The corrosion resistance of the cast Fe-5Cr-5Si alloy was fu...

The corrosion of three Fe-19Ni-21Cr-xAl (x = 0, 2, 6 at.%) alloys was studied at 900 °C in 10% CH4/H2 and 1.57% CH4/H2. All alloys followed complex kinetics. Addition of 2 at.% Al had a slight effect on the corrosion behaviour, while that of 6 at.% Al reduced the carbon attack, but was still insufficient to form protective Al2O3 scales. The concept...

The corrosion behaviors of as-cast Fe-5Cr-5Si alloy with and without sputtered Fe-5Cr-5Si film in H2-CO2-H2S mixture at 700 °C are studied. The corrosion scale forming on the as-cast alloy is non-protective and mainly composed of FeS outer layer and FeS + FeCr2O4 + Fe2SiO4 inner layer. However, a continuous Cr2O3 + SiO2 layer which possesses favora...

The oxidation of the Fe-5Cr-5Si and Fe-10Cr-5Si alloys has been examined under 1 and 10-20atm O2 at 700°C. In all cases the Cr additions improved the oxidation resistance of the Fe-5Si alloy by forming protective external scales rich in Cr- and Si-oxides, except for the oxidation of Fe-5Cr-5Si under the low oxygen pressure. Their scaling behavior h...

The oxidation of three Fe-xSi alloys (x = 5, 9, 13 at.%) under 10−20 atm O2 at 800 °C formed in all cases SiO2 layers. For Fe-5Si this layer broke down and healed up periodically forming an anomalous internal oxidation zone with spherical and net-shaped SiO2 particles. The SiO2 layer formed on the other two alloys spalled off due to the growth and...

The kinetics of the simultaneous internal oxidation of the reactive component of binary A–B alloys by two oxidants X–Y (double internal oxidation) in the presence of an external scale of a compound of the noble component A have been investigated theoretically and numerically on the basis of the theory of oxidation of binary alloys by a single oxida...

The corrosion behavior of three Fe–Si alloys containing approximately 5, 9 and 13 at.% Si was studied at 700 °C in an H2–CO2 gas mixture providing 10−20 atm O2 as well as in an H2–H2S–CO2 gas mixture providing the same oxygen pressure coupled to an S2 pressure of 10−8 atm. All the alloys followed complex kinetics which were mostly linear for Fe–5Si...

The oxidation of six Cu-xNi alloys (x = 0:2, 0.6, 1, 2, 3, 4 at.%) was studied at 800 °C under 1 atm O 2. All of the binary Cu-Ni alloys underwent an internal oxidation of Ni in the presence of an external scale of Cu 2O and CuO, in agreementwith the theoretical expectations for a finite range of Ni contents. However, the behavior of internal oxida...

The internal oxidation of Ni in dilute Cu–Ni alloys exposed to 1 atm. O2 at 900 °C, and thus in the presence of external CuOx scales, is absent for Ni levels below a critical value, extremely close to that required for the simultaneous equilibrium between the alloy and the oxides of the two components. For Ni contents not largely exceeding this lim...

Current protocols for Superovulation (SO) of rhesus monkeys are not optimized and outcomes vary considerably. There has been little attempt to predict SO outcome according to the stimulation starting time point (Day of cycle) of the candidate oocyte donors. In the present study, researchers focus on the SO initiation timing and we hypothesized that...

The objective of this study was to analysis the key factors which may be determinative to Superovulation (SO) in rhesus monkey. Total 361 rhesus monkeys were stimulated with recombinant human gonadotropins and Ova Pick Up (OPU) was conducted by laparoscopic follicular aspiration. Number of total ova and oocytes at Metaphase I (MI) and Metaphase II...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

An example of an isothermal thermodynamic phase diagram of a quaternary system composed of a binary alloy and two oxidants has been calculated under appropriate values of the stability of the corresponding compounds, assuming that each metal forms only one compound with each oxidant. Initially, two-dimensional sections of the complete three-dimensi...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

The oxidation under high pressures of a single oxidant of binary A–B alloys forming two insoluble oxides involves the internal oxidation of the most reactive component B when its concentration falls below an upper critical concentration defined by means of a criterion due to Wagner. However, this oxidation mode is no longer stable for alloys suffic...

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

A significant increase in nonhuman primate models of human diseases will be expected in the near future since the successes in production of genetically engineered rhesus monkey models of human diseases. Sperm banking can provide an effective way to preserve valuable genetic resources. Our objective was to (1) develop a protocol using directional f...

An improved treatment of the kinetics of coupled internal oxidation of the two most-reactive components of ternary alloys by a single oxidant, involving the presence of two different fronts of internal oxidation, as well as of the critical contents of these two components needed to avoid this oxidation mode, is developed both for the case of the ab...

The oxidation of four Ni–10Cr–ySi–4Al alloys was studied at 1100 °C to examine the effects of Si additions (from 2 to 6 at.%) on the behavior of the alloy Ni–10Cr–4Al. Addition of 2 at.% Si prevented completely nickel oxidation, but could not form alumina scales. Larger Si additions produced alumina only over part of the alloy surface (about 20% wi...

The oxidation of four Ni–10Cr–ySi–4Al alloys was studied at 1100 °C to examine the effects of Si additions (from 2 to 6 at.%) on the behavior of the alloy Ni–10Cr–4Al. Addition of 2 at.% Si prevented completely nickel oxidation, but could not form alumina scales. Larger Si additions produced alumina only over part of the alloy surface (about 20% wi...

Four ternary Cu–Zn–Al alloys containing 5 or 10 at.% Zn and 2 or 4 at.% Al plus an alloy containing 2 at.% Al and 15 at.% Zn have been oxidized at 800 °C in 1 atm O2, and their behavior has been compared with that of the corresponding binary Cu–Zn and Cu–Al alloys. For the alloy containing 4 at.% Al, which is already able to form external alumina s...

The corrosion of five Fe–Cr commercial steels containing 0–18wt.% Cr at 673–773K has been studied in a reducing H2–HCl–CO2 atmosphere under a ZnCl2–KCl deposit typical of waste gasification environments. In comparison with the behavior of the same steels in a similar gas mixture without salt deposit, all steels suffered from accelerated corrosion i...

Oxidation of five Cu–Zn alloys at 1,073K in 0.1MPa O2 showed the existence of three possible oxidation modes, including the internal oxidation of zinc beneath external CuO x scales, the growth of mixtures of the two oxides and the exclusive growth of external ZnO scales. The critical Zn contents required for the transitions between these oxidation...

The oxidation of four Ni–10Cr–ySi–4Al alloys has been studied in 1 atm O2 at 900 and 1000 °C to examine the effects of various Si additions on the behavior of the ternary alloy Ni–10Cr–4Al, which during an initial stage formed external NiO scales associated with an internal oxidation of Cr + Al, later replaced by the growth of a chromia layer at th...

The oxidation of an Fe–Al alloy containing 3at.% Al and of four ternary Fe–Cr–Al alloys with the same Al content plus 2, 3, 5 or 10at.% Cr has been studied in 1atm O2 at 1000°C. Both Fe–3Al and Fe–2Cr–3Al formed external iron-rich scales associated with an internal oxidation of Al or of Cr+Al. The addition of 3at.% Cr to Fe–3Al was able to stop the...

The corrosion behavior of five Fe–xCr–Al alloys with a constant Al content of 10 at.% and Cr contents ranging from 0 at.% to 20 at.% was examined at 600 °C in a H2–HCl–H2S–CO2 gas mixture providing 3.7 × 10−22 atm O2, 2.4 × 10−14 atm Cl2 and 3.9 × 10−9 atm S2. All the alloys formed duplex scales containing an outermost layer of iron oxide plus an i...

The simultaneous presence of sulfur and chlorine in an H2–HCl–H2S–CO2 reducing atmosphere accelerated the corrosion at 973 K of three Fe–xCr–10Al alloys (x = 0, 5, 10 at.%) with respect to their reaction with oxygen in an H2–CO2 mixture due to the growth of porous scales and a mixed internal attack of aluminum or of aluminum plus chromium. The chro...

The corrosion behaviour of pure iron, pure chromium, and aluminium/silicon alloyed Fe–Cr materials was investigated at 650 °C in air accompanied by gaseous or solid KCl salt. The corrosion rates of these materials with KCl salt are high and they are strongly affected by the salt amount, the types of the alloying elements and the concentration of ch...

The corrosion of three Fe–xCr alloys (x = 8, 12, 18 wt.%) was examined at 600 °C in reducing atmospheres containing HCl and H2S with two different H2S contents and compared with the behavior of the same materials in H2S–free H2–CO2 and H2–HCl–CO2 mixtures producing similar oxygen and chlorine pressures. Exposure to the low-H2S gas mixture had only...

The oxidation of Ni–xSi–10Al alloys (with x=0, 2, 4 and 6 at.%), has been studied at 900 and 1000°C in 1atm of pure O2 to examine the effect of different silicon additions on the behavior of ternary Ni–Si–10Al alloys. The kinetic curves of Ni–10Al are approximately parabolic at both 900 and 1000°C. Conversely, the kinetics of the ternary alloys at...

The rabbit, as a laboratory animal model, has several advantages in the study of human physiological disorders. In this study, stable putative pluripotent rabbit embryonic stem cells (rESCs) were derived from in vivo-fertilized and in vitro-cultured blastocysts. The rabbit ICMs were obtained by 0.05% trypsin–0.008% EDTA treatment and mechanical sep...

The oxidation of three Cu-Al alloys (Cu-1Al, Cu-2Al and Cu-3Al) containing 1, 2 and 3 at.% Al was studied at 1173K under 10-20 MPa O 2. The two binary Cu-Al alloys more dilute in aluminum underwent an internal oxidation of aluminum, contrary to the theoretical expectations which predicted an external growth of alumina scales. Furthermore, the rate...

The oxidation in 1 atm of pure oxygen of Ni–Cr–Al alloys with a constant aluminum content of 7 at.% and containing 5, 10 and 15 at.% Cr was studied at 900 and 1000 °C and compared to the behavior of the corresponding binary Ni–Al alloy (Ni–7Al). A dense external scale of NiO overlying a zone of internal oxide precipitates formed on Ni–7Al and Ni–5C...

The effect of alloy surface roughness, achieved by different degrees of surface polishing, on the development of protective alumina layer on Fe–10at.% Al alloys containing 0, 5, and 10at.% Cr was investigated during oxidation at 1000°C in 0.1MPa oxygen. For alloys that are not strong Al2O3 formers (Fe–10Al and Fe–5Cr–10Al), the rougher surfaces inc...

The conditions for the transition between the coupled internal oxidation of two most-reactive components and the formation of external scales in the scaling of ternary alloys under oxidant pressures below the stability of the oxide of the most-noble component, denoted as a situation of intermediate oxidant pressures, are examined under a number of...

Ternary A–B–C alloys, where A is the most-noble and C the most-reactive component, exposed to oxygen pressures above the stability of the least stable oxide AO (high-oxidant pressures) may present two different types of internal oxidation, i.e. either a coupled internal oxidation of both B and C beneath an external AO scale or a single internal oxi...

The oxidation of three Ni–xCr–10Al alloys with a constant Al content of 10 at% and containing 3, 5, and 10 at% Cr was investigated at 900–1000C in 1 atm of pure oxygen and compared to the behavior of Ni–10Al. At both temperatures, an external NiO scale overlying a zone of internal-oxide precipitates formed on Ni–10Al and Ni–3Cr–10Al: in addition, a...

The oxidation behavior of a binary Ni–6Al alloy and of three ternary Ni–xSi–6Al alloys containing 2, 4 and 6 at.% Si has been studied at 900°C under 1 atm of pure O2. The addition of 2 at.% Si to Ni–6Al increases the short-time oxidation rate of Ni–6Al, which is subsequently reduced and becomes similar to that of the binary alloy. However, the pres...

Oxidation of a Cu–2.2 at.%Al alloy (Cu–2Al) produces external scales containing Cu-oxides plus some alumina with almost no internal oxidation of aluminum. The addition of 3.9 at.%Cr to Cu–2Al has little effect on the oxidation behavior, while addition of 8.1 at.%Cr promotes a fast formation of an alumina layer in contact with the alloy with a simul...

The conditions for the formation of external alumina scales on binary Fe–Al alloys and the nature of the third-element effect due to chromium additions have been investigated by studying the oxidation at 1000°C in 1atm O2 of a binary Fe–10at.% Al alloy (Fe–10Al) and of two ternary Fe–Cr–10at.% Al alloys containing 5 and 10at.% chromium (Fe–5Cr–10Al...

The oxidation of three ternary Ni–6Si–xAl alloys containing 6, 10 and 15 at.% Al and of the corresponding binary Ni–Al alloys has been studied at 1000 °C under 1 atm O2 to examine the effect of different Al additions on the behavior of ternary Ni–Al–Si alloys containing 6 at.% Si. Of the three binary Ni–Al alloys only Ni–15Al was able to form exter...

The oxidation of three Cu–xCr–2Al and three Cu–xCr–4Al alloys (x ≅0,4,8at.%) has been investigated at 800°C in 1atm O2. Oxidation of a binary Cu–Al alloy containing 2.2at.% Al produced external scales composed mainly of copper oxides with small amounts of Al-rich oxide in the inner region, while the internal oxidation of Al was almost absent. The a...

The corrosion behavior of three Fe-15Cr-xAl alloys (x=0, 5, 10 at.%) beneath KCl-ZnCl2 deposits in air was investigated at 773K. All the alloys suffered from accelerated corrosion characterized by the formation of non-protective porous oxide scales. The addition of aluminum was only slightly beneficial for the corrosion resistance of the base alloy...

The oxidation behavior of a binary Cu-7Cr and a ternary Cu-7Cr-4Al alloy has been studied at 1173 K in 0.1 MPa O2 and compared with that of a binary Cu-4Al alloy. Oxidation of Cu-7Cr produced external copper oxide scales, while the internal oxidation of chromium was almost absent. The addition of 4 at.% Al to Cu-7Cr formed an alumina layer in conta...

The oxidation of four Ni–xSi–6Al alloys (x=0,2,4 and 6at.%) has been studied at 1273K under 0.1MPa O2. Silicon exerts the third-element effect by reducing the critical Al content needed for the transition from its internal to its external oxidation with respect to Ni–Al alloys. This result is interpreted by extending to ternary alloys Wagner’s crit...

The oxidation of two ternary Fe–Cu–Al alloys containing 10 at.% Al (Fe–65Cu–10Al and Fe–30Cu–10Al) has been studied at 800–900 °C under 1 atm O2. Under all conditions both alloys show an initial faster stage during which Fe–65Cu–10Al corrodes more rapidly at 800 °C than at 900 °C, while Fe–30Cu–10Al follows nearly identical kinetics at both tempera...

The oxidation in 105Pa of pure oxygen of three Ni-xCr-7Al alloys (x = 0,5,10 at.%) was studied at 1173K. A dense external scale of NiO overlying a zone of internal oxidation formed on Ni-7Al and Ni-5Cr-7Al. On the contrary, an external Al2O3 layer formed on Ni-10Cr-7Al. Thus, the addition of sufficient Cr levels to Ni-7Al produced a classical third...

The oxidation of two ternary Cu-Ni-Cr alloys containing approximately 30 and 40 at.% Cr, but with a similar Ni content, Cu-20Ni-30Cr and Cu-20Ni-40Cr, was studied at 973-1073 K in H2-CO2 mixtures providing an oxygen pressure of 10-19 atm, below the dissociation pressure of nickel and copper oxides. Both alloys are composed of a mixture of three pha...

The behavior of three commercial steels with different Cr contents (NF616, 12CrMoV and SS304) at 873K in a gas mixture of (vol.%) 2 H2, 0.5 HC1, 0.005 H2S, balance CO2, providing partial pressures of 3.7×10-22 atm O2, 3.9×10 -9 atm S2 and 2.4×10-14 atm Cl 2, has been studied to examine the effect of a minor addition of H2S to a reducing HCl-contain...

The transient oxidation behavior of β-NiAl and NiAl-0.5Ag in 1 atm O2 at 1273K was studied by thermogravimetry, giving special emphasis to the evolution of the morphology of the oxide scale, especially for what concerns the transformation of transient aluminas into the stable α-Al2O3 form. The oxidation kinetics can be described as being composed o...

The kinetics of the simultaneous internal oxidation of the two most-reactive components B and C in ternary A–B–C alloys, where A is the most-noble and C the most-reactive component, in the presence of an external layer of the A oxide, AO, (high oxidant pressures) are examined assuming the existence of either a single or a double front of internal o...

The corrosion of four Fe–Cr commercial steels with different chromium contents in a simulated waste-gasification atmosphere containing 0.5 vol. H2, 0.5 vol. HCl, balance CO2 has been investigated at 773 and 873 K. The same materials have also been tested in the same gas mixture free from HCl at both temperatures for comparison. The results show tha...

The kinetics of internal oxidation of the most-reactive component C of ternary A–B–C alloys in the presence of external scales of the oxide of the component of intermediate reactivity B, BO?, are examined using convenient approximations. The precipitation of the most-stable oxide leaves behind a matrix composed of a mixture of the two most-noble co...

This paper examines the conditions for the transition from internal to external oxidation of the most-reactive component C of ternary A–B–C alloys by a single oxidant under gas-phase oxidant activities below the stability of the oxide of the two most-reactive components using Wagner’s criterion. For this, approximate relations between the solubilit...

The conditions for the transition from internal to external oxidation of the most-reactive component C of ternary A–B–C alloys are examined, assuming the presence of external scales of the oxide of the component of intermediate reactivity B. For this, approximate expressions for the diffusion coefficient of oxygen and for the concentration of oxyge...

CCSD logging engineering gather many modern high technologies and employs various advanced logging tools to survey the sidewall continuously. This can obtain various physical, chemical, geometrical, etc in-situ information of the borehole's profile. So well logging is one of the most important parts and pivotal technologies in the project of CCSD....

The oxidation of two ternary Cu–Ni–Cr alloys containing approximately 30 and 40 at.% Cr, but with a similar Ni content, was studied at 700–800 °C in 1 atm of pure oxygen. Both alloys contain a mixture of three phases, where the phase with the largest copper and lowest chromium content (α) forms the matrix, while the phase with an intermediate conte...

The oxidation of the ternary alloys Ni-45Cu-10Al and Ni-30Cu-10Al has been studied at 800-900 degreesC under 1 atm O-2. The presence of 10 at.% Al reduces significantly the oxidation rate of the corresponding Cu-Ni alloys during the initial oxidation stages, even before the establishment of a complete Al2O3 layer. The weight of individual sample of...

The oxidation of two two-phase ternary Fe–Cu–Al alloys containing about 5 at.% aluminium, one Fe-rich and one Cu-rich, has been studied at 800°C under 1 atm O2. The Fe-rich alloy (Fe–15Cu–5Al) shows two parabolic stages, with a large decrease of the parabolic rate constant after about 2 hr. The presence of 5 at.% Al reduces significantly the oxidat...

Corrosion behaviors of pure Ni and three NiCr alloys were investigated in an HCl-containing oxidizing atmosphere at 700°C and 800°C. All materials suffer from accelerated corrosion at both temperatures. NiCr alloys show an initial mass loss due to the formation of volatile CrCl3 and CrO2C12. Some chlorides are detected at the scale/substrate interf...

The kinetics of the coupled internal oxidation of the two most-reactive components in the scaling of ternary alloys under oxidant pressures below the stability of the oxide of the most noble component are examined using a number of simplifying conditions which allow to develop an approximate analytical treatment. The precipitation of the two oxides...

The internal oxidation of the most-reactive component C of ternary A–B–C alloys by a single oxidant is examined assuming a gas-phase oxidant pressure below the stability of the oxides of the other two components. The precipitation of the most-stable oxide leaves behind a matrix composed of a binary alloy of the two less-reactive components, whose c...

After considering briefly the phase diagrams of ternary systems involving two metal components and one oxidant and the limitations to their use in relation to the high temperature oxidation of binary alloys, the paper examines the construction of other plots, denoted as kinetic diagrams, useful to predict under which conditions the two oxides, assu...

The oxidation of a Ni-rich and a Cu-rich single-phase ternary alloy containing about 5at.% aluminum has been studied at 800 and 900C under 1atm O2. The behavior of the Ni-rich alloy is similar to that of a binary Ni–Al alloy with a similar Al content at both temperatures, with formation of an external NiO layer coupled to the internal oxidation of...

Two nanocrystalline two-phase Cu–Ni–Cr alloys, both prepared by mechanical alloying and containing about 20 at.% Cr but with different Ni contents (40 and 20 wt.%, respectively), have been oxidized in 1 atm O2 at 700–800 °C. Their oxidation behavior has been compared with that of two cast alloys of the same composition, already studied previously,...

Tonga and Mariana forearc peridotites, inferred to represent their respective subarc lithospheres, are compositionally highly depleted (low Fe/Mg) and thus physically buoyant relative to abyssal peridotites representing normal oceanic lithosphere (high Fe/Mg) formed at ocean ridges. The observation that the depletion of these forearc lithospheres i...

Consideration of petrology, geochemistry, and mineral physics suggests that ancient subducted oceanic crusts cannot be the source materials supplying ocean island basalts (OIB). Melting of oceanic crusts cannot produce high-magnesian OIB lavas. Ancient oceanic crusts (>1 Ga) are isotopically too depleted to meet the required values of most OIB. Sub...

Geological processes are consequences of the Earth’s thermal evolution. Plate tectonics, which explain geological phenomena along plate boundaries, elegantly illustrate this concept. For example, the origin of oceanic plates at ocean ridges, the movement and growth of these plates, and their ultimate consumption back into the Earth’s interior throu...

The oxidation behaviors of Cu-Cr alloys prepared by powder metallurgy (PM Cu-25Cr), mechanically alloying (MA Cu-20Cr) and magnetron sputtering (MS Cu-20Cr) techniques in 0.1 MPa O-2 at 700 degreesC were investigated. A complex scale composing of CuO, Cu2O, CuCr2O4 and Cr2O3 formed on the PM Cu-25Cr alloy, a continuous Cr2O3 layer beneath a complex...

The oxidation of a Cu–Cr alloy containing about 60 wt% Cr and of two Cu–Cr alloys containing about 40 wt% Cr was studied at 700 and 800 °C in 1 atm O2. The 60 wt% Cr alloy was prepared by powder metallurgy (PM) and had a phase particle size of 50–150 μm. One of the two alloys containing about 40 wt% Cr was prepared by mechanical alloying (MA) and h...

Corrosion problems in waste incinerators are usually rather severe, also due to the presence of low-melting point heavy and alkali metal chlorides. In this paper, the corrosion behavior of several Fe-based alloys with different Cr content, as well as three pure metals Fe, Cr, and Ni, was studied at 450 °C beneath ZnCl2–KCl deposits in flowing pure...

Pores, or voids, at oxide–alloy interfaces are commonly observed after high temperature oxidation when the alloy does not contain a reactive element. In order to understand the pore-nucleation and growth processes, the density, size and depth of interfacial pores on Fe–40 at.%Al as a function of oxidation time at 1000C were examined. Scanning-elect...

A bulk nanocrystallined Ag50Ni alloy has been prepared by hot-pressing the mechanically pre-alloyed powders at 620 °C under a normal pressure of 58 MPa in vacuum. The microstructural characteristics of the alloy were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results of the...

The oxidation behavior of thin layers of two Cu–Fe alloys containing 25 and 50 wt.% Fe, respectively, prepared by magnetron sputtering deposition on cast alloys of the same composition (Cu–Fe coatings) and presenting grain sizes in the nanometer range, was studied at 600–800 °C in air to examine the influence of the reduction in the grain size on t...

Niu and Batiza [Earth Planet. Sci. Lett. 148 (1997) 471–483] show that lavas from the seamounts on the flanks of the East Pacific Rise (EPR) between 5° and 15°N vary from extremely depleted tholeiites to highly enriched alkali basalts. The extent of depletion and enrichment exceeds the known range of seafloor lavas in terms of the abundances and ra...

The oxidation of a ternary Cu–Ni–Cr alloy containing approximately 45 wt.% Ni and 30 wt.% Cr has been studied in 1 atm O2 at 700–800°C. The alloy contains a mixture of three phases: the one with the largest copper and lowest chromium content forms the matrix, the one with an intermediate chromium content has a rather large volume fraction and forms...

The corrosion of a Fe-15 wt.% Ce alloy and of the two pure metals have been studied at 600 to 800 °C in H2-H2S-CO2 mixtures providing high-sulfur and low-oxygen activities that are typical of coal gasification atmospheres. The alloy corrodes more slowly at 600 to 700 °C than pure Fe, more rapidly than pure Ce, while at 800 °C it corrodes at about t...

The general properties of the isothermal thermodynamic phase diagrams for ternary A–B–C alloys exposed to a single oxidant at high temperatures are examined, assuming, for simplicity, the formation of insoluble p-type oxides, an ideal behavior of the alloy, and a common value of the self-diffusion coefficient for the alloy components, independent o...

We present trace element (ICP-MS) and high-precision (triple-spike) Pb isotope data for a suite of 28 fresh glasses from a single segment of the MAR at 26° S, and from near-ridge seamounts in the same area. The samples have previously been analysed for major elements and Sr-Nd-He isotopes (Castillo and Batiza, 1989; Niu and Batiza, 1994; Graham et...

The oxidation of a ternary Cu-Ni-Cr alloy containing approximately 20 wt% Ni and 20 wt% Cr (Cu-20Ni-20Cr) and composed of a mixture of three phases has been studied in 101 kPa (1 atm) O2 at 973-1073 K. The alloy matrix was composed of the phase with the largest copper and lowest chromium content, while the other two phases, much richer in chromium,...

Two ternary Cu–Ni–Cr alloys containing approximately 20 wt.% chromium, but with a different Cu and Ni content, have been oxidized in 1 atm of pure oxygen at 700–800C. The alloy containing about 60 wt.% nickel (Cu–60Ni–20Cr) was composed of a single solid-solution phase and formed external scales of chromium ocide with an outermost layer containing...

The effect of grain size reduction on the high temperature oxidation of binary two-phase alloys was discussed based on the recent research progress. The results show that for those two-phase alloy with coarse grain prepared by the conventional methods, complex oxide scales are easily formed after oxidation under high oxygen pressure or under oxygen...

A bulk nanocrystailine Ag50Ni50 alloy has been prepared by hot pressing of mechanically alloyed powder at 620 °C under a pressure of 58 MPa. The microstructural characteristics of the alloy were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show. that after mechanical...

The oxidation of two Cu–Ni–Ag alloys in air has been studied at 600–700°C. Both alloys contain a mixture of a silver-rich phase (α) with a second phase mostly composed of a copper–nickel solid solution (β). Thus, these alloys are ternary two-phase systems containing two reactive metals with different affinity for oxygen plus a noble metal. Under al...

The air oxidation of Cu-Ni alloys with 50% and 70% nickel (mole fraction) at 800°C was studied. The kinetic curves for the oxidation of the two alloys are complex and deviate from the parabolic rate law. Typical double-layered scales are produced, which consist of a CuO outer layer and an inner layer containing a mixture of Cu2O and NiO with many p...

The oxidation of PM Cu-50Cr, MA Cu-40Cr and MS Cu-40Cr alloys at 800°C in 0.1 MPa O2 was studied. The most important difference of the oxidation behaviors is the formation of an exclusive chromia scale on the surface of the MS Cu-40Cr alloy and a continuous chromia layer beneath an outer CuO layer corresponding MA Cu-40Cr alloy, while a complex sca...

Mantle temperature variation and plate spreading rate variation have been considered to be the two fundamental variables that determine the extent of mantle melting and ocean crust production. Along the length of a 200 km portion of the Mid-Atlantic Ridge (MAR) between the Oceanographer (35°N) and Hayes (33°N) transforms, the mantle potential tempe...

A silver-based alloy containing about 8 wt% Y (Ag–8Y) has been oxidized under 1 atm and 10−20 atm O2 at 700°C. The alloy contains a mixture of a solid solution of Y in Ag (α phase) with an eutectic mixture of the α phase with the intermetallic compound Ag51Y14 (β phase). The oxidation rate in 1 atm O2 is very fast and follows the parabolic rate law...

The oxidation of a Cu-based ternary alloy containing 30 at% Ni and 25 at% Fe has been studied at 800–900°C under low oxygen pressures. The alloy contains a mixture of a phase α rich in Cu and Ni with little Fe with a phase β rich in Fe and Ni with little Cu. The scaling kinetics show rather large deviations from the parabolic law and are much slowe...

The air oxidation of two two-phase cobalt-copper alloys prepared by mechanical alloying, containing approximately 50 wt%Cu but presenting two different grain sizes, has been studied at 600-800°C. The two alloys have been obtained by sintering a mixture of nanophase Co-Cu powders by hot isostatic pressing followed or not by an annealing at 800°C for...