Observation of second-phase particles in bulk zirconium alloys using synchrotron radiation

2001 ◽  
Vol 294 (3) ◽  
pp. 299-304 ◽  
Author(s):  
Kenneth T. Erwin ◽  
Olivier Delaire ◽  
Arthur T. Motta ◽  
Yong S. Chu ◽  
Derrick C. Mancini ◽  
...  
Keyword(s):  
Synchrotron Radiation ◽  
Zirconium Alloys ◽  
Second Phase ◽  
Second Phase Particles

scholarly journals Evidence of hydrogen trapping at second phase particles in zirconium alloys

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Christopher Jones ◽  
Vidur Tuli ◽  
Zaheen Shah ◽  
Mhairi Gass ◽  
Patrick A. Burr ◽  
...  
Keyword(s):  
Density Functional ◽  
Secondary Ion Mass Spectrometry ◽  
Zirconium Alloys ◽  
Nuclear Industry ◽  
Second Phase ◽  
Hydrogen Trapping ◽  
Functional Theory ◽  
Second Phase Particles ◽  
Hydrogen Isotope Ratios ◽  
Dft Modelling

AbstractZirconium alloys are used in safety–critical roles in the nuclear industry and their degradation due to ingress of hydrogen in service is a concern. In this work experimental evidence, supported by density functional theory modelling, shows that the α-Zr matrix surrounding second phase particles acts as a trapping site for hydrogen, which has not been previously reported in zirconium. This is unaccounted for in current models of hydrogen behaviour in Zr alloys and as such could impact development of these models. Zircaloy-2 and Zircaloy-4 samples were corroded at 350 °C in simulated pressurised water reactor coolant before being isotopically spiked with 2H2O in a second autoclave step. The distribution of 2H, Fe and Cr was characterised using nanoscale secondary ion mass spectrometry (NanoSIMS) and high-resolution energy dispersive X-ray spectroscopy. 2H− was found to be concentrated around second phase particles in the α-Zr lattice with peak hydrogen isotope ratios of 2H/1H = 0.018–0.082. DFT modelling confirms that the hydrogen thermodynamically favours sitting in the surrounding zirconium matrix rather than within the second phase particles. Knowledge of this trapping mechanism will inform the development of current understanding of zirconium alloy degradation through-life.

Effect of Bi Addition on the Corrosion Behavior of Zirconium Alloys

2013 ◽  
Author(s):  
M. Y. Yao ◽  
B. X. Zhou ◽  
Q. Li ◽  
W. P. Zhang ◽  
L. Zhu ◽  
...  
Keyword(s):  
Solid Solution ◽  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Mass Fraction ◽  
Zirconium Alloys ◽  
Deionized Water ◽  
Second Phase ◽  
Micro Structure ◽  
Second Phase Particles ◽  
Structure Observation

In order to investigate systematically the effect of Bi addition on the corrosion resistance of zirconium alloys, different zirconium-based alloys, including Zr-4 (Zr-1.5Sn-0.2Fe-0.1Cr), S5 (Zr-0.8Sn-0.35Nb-0.4Fe-0.1Cr), T5 (Zr-0.7Sn-1.0Nb-0.3Fe-0.1Cr) and Zr-1Nb, were adopted to prepare the zirconium alloys containing Bi of 0∼0.5% in mass fraction. These alloys were denoted as Zr-4+xBi, S5+xBi, T5+xBi and Zr-1Nb+xBi, respectively. The corrosion behavior of these specimens was investigated by autoclave testing in lithiated water with 0.01 M LiOH or deionized water at 360°C/18.6 MPa and in superheated steam at 400 °C/10.3 MPa. The micro structure of the alloys was examined by TEM and the second phase particles (SPPs) were analyzed by EDS. Micro structure observation shows that the addition of Bi promotes the precipitation of Sn as second phase particles (SPPs) because Sn is in solid solution in α-Zr matrix in Zr-4, S5 and T5 alloys. The concentration of Bi dissolved in α-Zr matrix increase with the increase of Nb in the alloys, and the excess Bi precipitates as Bi-containing SPPs. The corrosion results show that the effect of Bi addition on the corrosion behavior of different zirconium-based alloys is very complicated, depending on their compositions and corrosion conditions. In the case of higher Bi concentration in α-Zr, the zirconium alloys exhibit better corrosion resistance. However, in the case of precipitation of Bi-containing SPPs, the corrosion resistance gets worse. This indicates that the solid solution of Bi in α-Zr matrix can improve the corrosion resistance, while the precipitation of the Bi-containing SPPs is harmful to the corrosion resistance.

scholarly journals Homogenization and Growth Behavior of Second-Phase Particles in a Deformed Zr–Sn–Nb–Fe–Cu–Si–O Alloy

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 759 ◽  
Author(s):  
Liang-Yu Chen ◽  
Peng Sang ◽  
Lina Zhang ◽  
Dongpo Song ◽  
Yan-Qiu Chu ◽  
...  
Keyword(s):  
Ostwald Ripening ◽  
Short Circuit ◽  
Zirconium Alloys ◽  
Lattice Diffusion ◽  
Growth Behavior ◽  
Homogeneous Distribution ◽  
Second Phase ◽  
Deformation Degree ◽  
Linear Distribution ◽  
Second Phase Particles

Homogeneous distribution of fine second-phase particles (SPPs) fabricated by cycles of deformation and annealing in zirconium alloys is a critical consideration for the corrosion resistance of fuel claddings. Different deformation degrees of zirconium alloys would result in distinctive microstructures, leading to a distinct growth of SPPs during subsequent annealing. Unfortunately, the homogenization and growth behavior of SPPs in deformed zirconium alloys have not been well studied. In this work, a β-quenched Zr–Sn–Nb–Fe–Cu–Si–O alloy was rolled and annealed at 580 °C or 680 °C. The morphologies, distributions, and sizes of SPPs resulting from the different processing procedures were investigated. A linear distribution of SPPs is found in the β-quenched sample. Afterward, SPPs grow and are randomly distributed during heat treatment as the deformation degree or annealing time (or temperature) increases. The homogenization and growth of SPPs are attributed to the Ostwald ripening mechanism that is governed by lattice diffusion and short-circuit diffusion. The sample with a higher deformation degree is speculated to have a larger number of defects that provide more shortcuts for the mass transfer of SPPs, thereby facilitating a homogeneous distribution of fine SPPs during annealing.

scholarly journals Study on Microstructure and Fatigue Properties of FGH96 Nickel-Based Superalloy

Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6298
Author(s):  
Yishan Bai ◽  
Shanglei Yang ◽  
Minqi Zhu ◽  
Cong Fan
Keyword(s):  
Synchrotron Radiation ◽  
Cleavage Fracture ◽  
Damage Mechanism ◽  
Propagation Path ◽  
Fatigue Properties ◽  
Second Phase ◽  
X Ray ◽  
Nickel Based Superalloy ◽  
Second Phase Particles ◽  
Cleavage Step

In this study, using synchrotron radiation X-ray imaging, the microstructure, tensile properties, and fatigue properties of FGH96 nickel-based superalloy were tested, and the fatigue damage mechanism was analyzed. An analysis of the experimental results shows that the alloy structure is dense without voids or other defects. It was observed that the primary γ′ phase is distributed on the grain boundary in a chain shape, and the secondary γ′ phase is found inside the crystal grains. The X-ray diffraction (XRD) pattern indicates that no other phases were seen except for the γ and γ′ phases. The tensile strength of the alloy is 1570 MPa and the elongation is 12.1%. Using data fitting and calculation, it was found that the fatigue strength of the alloy under the condition of 5 × 106 cycles is 620.33 MPa. A fatigue fracture has the characteristics of secondary crack, cleavage step, fatigue stripe, tire indentation, and dimple. The fracture is a mix of cleavage fracture and ductile fracture. Through a three-dimensional reconstruction of the alloy synchrotron radiation imaging area, it was found that the internal defects are small and mostly distributed at the edge of the sample. The dimple morphology is formed by cavity aggregation and cavity germination resulting from defects in the material itself, fracture of the second-phase particles, and separation of the second-phase particles from the matrix interface. By analyzing the damage mechanism of fatigue fractures, it is concluded that the cleavage step is formed by the intersection of cleavage planes formed by branch cracks, with the main crack of the confluence extending forward to form a cleavage fracture. The crack propagation path was also analyzed, and under the action of cyclic load and tip passivation, the crack shows Z-shaped propagation.

The influence of second phase particles on the crack formation in oxide films formed on zirconium alloys

2015 ◽  
Vol 99 ◽  
pp. 172-177 ◽  
Author(s):  
Jiao Huang ◽  
Mei-yi Yao ◽  
Chang-yuan Gao ◽  
Xue Liang ◽  
Jian-chao Peng ◽  
...  
Keyword(s):  
Crack Formation ◽  
Oxide Films ◽  
Zirconium Alloys ◽  
Second Phase ◽  
Second Phase Particles
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