Showing papers on "Zirconium alloy published in 1970"
TL;DR: In this article, the authors measured the stresses in oxide films on Zircaloy-2 and zirconium crystal bar after oxidation in the temperature range 500-700 °C.
102 citations
01 Jan 1970
TL;DR: In this paper, the effect of strain rate on the plastic flow behavior was examined by means of tension tests over a range of temperatures (RT {¯¯ � $$ \sim $$====== } 500°C).
Abstract: The effect of strain rate (10−5 {
$$ \sim $$
} 10−1 min−1) on the plastic flow behavior was examined by means of tension tests over a range of temperatures (RT {
$$ \sim $$
} 500°C). The principal material examined was Zircaloy-2, and the others were iodide zirconium and binary alloys of Zr-0.1 pct O and Zr-1.5 pct Sn by weight. In Zircaloy-2, the behavior was characterized by a sudden increase of flow strength with decreasing strain rate; concurrently the ductility decreased. Other interrupted and hold time experiments showed that the process is essentially that of a strain rate-induced strengthening phenomenon, with several features which could be identified with the strain aging process. It was further shown that the critical range of strain rates and temperatures at which the anomalous behavior took place could be correlated with the minimum in the strain rate sensitivity of flow stress. A similar but less pronounced flow behavior was observed with pure zirconium and its binary alloys, but with no marked change in the tensile ductility. From these results, the role of oxygen and tin on the early stage of plastic flow behavior was discussed in terms of dislocation-impurity interaction mechanisms. It was however concluded that these elements are not directly responsible for the ductility loss at slow strain rate in Zircaloy-2.
98 citations
TL;DR: In this article, the deformation kinetics of zirconium and Zircaloy-2 strips, resulting from oxidation at 500°C in dry oxygen, were measured as a function of time.
Abstract: The deformation kinetics of zirconium and Zircaloy-2 strips, resulting from oxidation at 500°C in dry oxygen, were measured as a function of time. The stress distribution in the oxidized specimens was analyzed using a stress model based on the theory of elasticity and was correlated with the oxidation kinetics. The magnitude of the stress generated during oxidation differed significantly between zirconium and Zircaloy-2; while a simple linear relationship appeared to exist between the stress and the oxide thickness on zirconium, the stresses in oxides on Zircaloy-2 increased very rapidly and discontinuously to a maximum at a film thickness near the transition in the kinetic curve. In order to characterize the stress distribution in the oxide film, vacuum annealing experiments were performed on preoxidized specimens. These indicated that the stress relaxation which occurs during vacuum annealing resulted from dissolution in the metal of the highly stressed inner layers of the oxide film. Although these measurements have provided valuable information on the stresses generated during the oxidation of zirconium and Zircaloy-2, they do not require a causal relationship between the stresses and any oxidation process (e.g., transition).
81 citations
TL;DR: In this paper, X-ray diffraction studies by both reflection and transmission techniques were made on oxide films formed on crystal-bar zirconium and Zircaloy-2 in oxygen at 500 °C.
73 citations
TL;DR: Li's theory of stress orientation of disc shaped precipitates is applied to the problem of stress orientations of hydride in zirconium alloys as mentioned in this paper, and the experimental observations are shown to be consistent throughout.
60 citations
TL;DR: In this article, the I-V curves obtained in a molten salt have been determined at 175-350 °C for oxidation films on zirconium alloys. But the results were discussed in relation to the in-reactor enhancement of the oxidation rate of Zircaloy-2 in aqueous environments containing oxygen.
55 citations
TL;DR: In this paper, the effect of zirconium carbide in causing basketweave structure was confirmed in full scale production of Zircaloy by adding carbon to a melt of low carbon zirconsium sponge.
42 citations
40 citations
TL;DR: A comprehensive review of the literature concerning zirconium and hafnium can be found in this paper, which takes the reader up to about 1960, although references to earlier work are included where necessary to complete the picture.
Abstract: Publisher Summary There are several complete compilations of the literature concerning zirconium and hafnium that take the reader up to about 1960. Since then several reviews of more limited scope have been published, one on the structural aspects of zirconium chemistry, and others on the separation of zirconium and hafnium aqueous chemistry , and ion-exchange properties of zirconium compounds. In general, the data in the present review are drawn from publications since 1960, although references to earlier work are included where necessary to complete the picture. The discovery that the thermal-neutron cross-section capture of zirconium containing the natural 2% hafnium content was largely due to the very high thermal-neutron cross section of the hafnium stimulated the present interest in the chemical and physical properties of these elements. The use of hafnium-free zirconium alloys for cladding nuclear fuels and the use of hafnium for control rods in nuclear reactors account for the fact that much of the recent literature deals with the reduction, purity, working properties, and alloy formation of these elements.
37 citations
TL;DR: The annealing textures in Zircaloy tubing are more complex than those reported for rolled and annealed zirconium or titanium sheet as mentioned in this paper, due to the variations in deformation temperature, degree of deformation, and deformation method.
28 citations
TL;DR: In this paper, it was shown that irradiation enhances the corrosion of Zircaloy 2 and Zr-2 1/2% Nb alloy by 10-fold or more.
TL;DR: In this paper, it has been shown that the oxidation of crystal-bar zirconium is limited by electron transport through oxide and across the outer oxide surface between electronic flaws in the oxide and the sites of oxygen reduction.
TL;DR: In this paper, the X-ray parametric method was used to determine the solvus curve in the zirconium rich region of the Zr-Al system, down to temperatures lower than 700 °C.
01 Jan 1970
TL;DR: In this paper, a Zirconium core was coated with zirconia hydride and allowed to equilibrate at 689 °K. The concentration of hydrogen (at %) after n cycles is C H = (8.14 + 1.13 n) 1 3 for slow heating and cooling when the specimen is allowed to remain at 6 89 °K long enough for equilibration.
TL;DR: The hardness response and structure of high-purity and commercial purity Zr/2.5 wt% Nb alloys have been studied as a function of aging treatment as discussed by the authors.
TL;DR: A 1.2-2 fold enhancement of the corrosion rate of Zircaloy-2 in steam at atmospheric pressure by an applied tensile stress in the metal has been observed at 475 and 400 °C but not at 350 °C as mentioned in this paper.
TL;DR: In this article, simple methods are described for predicting the approximate distribution of hydrogen in zirconium alloy components subjected to a temperature gradient whilst corroding, and applied to typical fuel cladding operating in a water-cooled nuclear reactor they indicate that precipitation of hydride should be restricted to the outer layers of the cladding.
Patent•
25 May 1970
TL;DR: Nickel-molybdenum alloys have increased corrosion resistance and resistance to impact at room temperature and below resulting from a critical control of the amounts of carbon, silicon, vanadium, boron and zirconium without creating vanadium stabilization as mentioned in this paper.
Abstract: Nickel-molybdenum alloys having increased corrosion resistance and resistance to impact at room temperature and below resulting from a critical control of the amounts of carbon, silicon, vanadium, boron and zirconium without creating vanadium stabilization. The carbon and silicon are maintained in negligible amounts and the vanadium, boron and zirconium are closely controlled.
TL;DR: In this paper, the solubility of hydrogen has been determined in the (Zr + 2.5 wt % Nb)-H2 system as a function of composition, temperature and hydrogen equilibrium pressure (0.5-760 mm Hg).
TL;DR: In this paper, the oxidation behavior of Zirconium-niobium alloys in pressurised water at 300° indicate a sensitivity to oxygen content of the water and niobium content of Zircaloy-2 alloy which can be reconciled with the concept of an oxide film of duplex type.
Abstract: Observationson the oxidation behaviour of zirconium-niobium alloys in pressurised water at 300° indicate a sensitivity to oxygen content of the water and niobium content of the alloy which can be reconciled with the concept of an oxide film of duplex type, the inner portion being of the normal hypostoicheiometric n-type but changing unnder the relatively oxidising conditions in the outer layers to a hyperstoicheiometric p-type oxide contaning Interstitial oxygen ions by virtue of the presence of some Nbv ions.There are also preliminary indications of a similar type of sensitivity of corrosion rate to oxygen content of the water wIth a 0·75 wt.-% zIrcomum-ehromium alloy. Experiments carried out with Zircaloy-2 at 290° in water dosed with chromium trioxide and with a 1500 lb/in2 overpressure of oxygen to produce chromate ions in solution have shown an increase in corrosion rate suggesting that doping of the zirconia film with higher valent chromium ions is occurring during the test.There are analog...
01 Jan 1970
TL;DR: In this article, a thermodynamic analysis of the relative positions of the α, β, ω transus lines and corresponding αM s and ω start curves is presented.
Abstract: The available characteristics of the pressure-induced omega transformation in pure titanium and zirconium, and the behaviour of omega in alloy systems, are combined to give an interpretation of omega formation in terms of a peritectoid reaction. This allows the omega-phase to be derived from the properties of the parent lattice, but also yields a specific region of stability which may coincide with a characteristic electron-concentration. The critical temperature associated with the peritectoid reaction offers an explanation for the upper temperature limit observed for the omega phase on heating metastable beta alloys. A thermodynamic analysis of the relative positions of the α, β, ω transus lines and the corresponding αM s and ω start curves shows that it is the α M s which largely dictates the onset of ω formation on cooling. Hence the composition of the hardness peak on quenching is largely controlled by the limited solubility of solute in the α-phase. A full delineation of the peritectoid in titanium alloys is not possible owing to insufficient experimental data. However, the region of omega stability at 400°C has been determined by analysing plateau hardness values and lattice parameters of quenched and tempered alloys of varying solute content. The proportion of ω in tempered β reflects the maximum solute solubility in these two phases. Neither electron-concentration nor size considerations can properly account for the full extent of omega stability, which encompasses the pure solvent under suitable conditions of temperature and pressure.