Examinations of the Corrosion Mechanism of Zirconium Alloys

When zirconium alloy is corroded, an oxide film is formed on the surface, which hinders the ion transfer during the corrosion process. Therefore, the analysis of the oxide film is an important part of the research on the corrosion resistance of zirconium alloys. In this paper, two kinds of Zr-Sn-Nb alloys were corroded in 400 °C/10.3 MPa pure steam and 500 °C/10.3 MPa pure steam in autoclave to obtain samples with oxide thickness of 14 um and 18 um respectively. Then they were annealed at 800 °C at a pressure of 10-4 Pa for 18 h. XRD and WDS studies were used to analyze the structure and oxygen content of the oxide film after annealing. The results indicate that the oxide films of alloys change from zirconium dioxide to zirconium after annealing. The oxygen diffuses into the substrate and its content decreases continuously with increasing diffusion distance. Combined with the SEM analysis of cross-section samples, it is found that the annealed samples are composed of several layers. An oxygen-saturated zirconium layer, a transitional layer with micro-cracks, an oxygen-dissolved α-Zr layer and a β-Zr layer are identified. Based on these results, the mechanism of the ion transfer in the oxide film during annealing is analyzed deeply. It is proposed that space charges in the oxide film have a major impact on deoxidation kinetics. This study provides a new research method for the corrosion mechanism of zirconium alloys.

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Control of hydrogen absorption by nickel films obtained upon magnetic spraying of zirconium alloy using the thermoEMF method

Industrial laboratory Diagnostics of materials ◽

10.26896/1028-6861-2020-86-8-32-37 ◽

2020 ◽

Vol 86 (8) ◽

pp. 32-37

Author(s):

V. V. Larionov ◽

Xu Shupeng ◽

V. N. Kudiyarov

Keyword(s):

Magnetron Sputtering ◽

Hydrogen Concentration ◽

Hydrogen Absorption ◽

Zirconium Alloy ◽

Hydrogen Adsorption ◽

Zirconium Alloys ◽

Nickel Film ◽

Protective Film ◽

Nickel Films ◽

Hydrogen Penetration

Nickel films formed on the surface of zirconium alloys are often used to protect materials against hydrogen penetration. Hydrogen adsorption on nickel is faster since the latter actively interacts with hydrogen, oxidizes and forms a protective film. The goal of the study is to develop a method providing control of hydrogen absorption by nickel films during vacuum-magnetron sputtering and hydrogenation via measuring thermoEMF. Zirconium alloy E110 was saturated from the gas phase with hydrogen at a temperature of 350°C and a pressure of 2 atm. A specialized Rainbow Spectrum unit was used for coating. It is shown that a nickel film present on the surface significantly affects the hydrogen penetration into the alloy. A coating with a thickness of more than 2 μm deposited by magnetron sputtering on the surface of a zirconium alloy with 1% Nb, almost completely protects the alloy against hydrogen penetration. The magnitude of thermoemf depends on the hydrogen concentration in the zirconium alloy and film thickness. An analysis of the hysteresis width of the thermoEMF temperature loop and a method for determining the effective activation energy of the conductivity of a hydrogenated material coated with a nickel film are presented. The results of the study can be used in assessing the hydrogen concentration and, hence, corrosion protection of the material.

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Experimental Investigation of the Corrosion Mechanism of Cemented Soils in Magnesium Sulfate Solution

Materials Testing ◽

10.3139/120.110616 ◽

2014 ◽

Vol 56 (9) ◽

pp. 675-680 ◽

Cited By ~ 1

Author(s):

Pengju Han ◽

Y. Frank Chen ◽

Bozhu Shen ◽

David Y. Du

Keyword(s):

Experimental Investigation ◽

Magnesium Sulfate ◽

Sulfate Solution ◽

Corrosion Mechanism ◽

Cemented Soils ◽

Magnesium Sulfate Solution

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Typical Zirconium Alloys Microstructures in Nuclear Components

Practical Metallography ◽

10.3139/147.110304 ◽

2014 ◽

Vol 51 (9) ◽

pp. 656-674 ◽

Cited By ~ 3

Author(s):

A. V. Flores ◽

A. G. Gomez ◽

G. A. Juarez ◽

N. Loureiro ◽

R. I. Samper ◽

...

Keyword(s):

Zirconium Alloys

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An Overview of Cu Wire Intermetallic Compound Formation and a Corrosion Failure Mechanism

ISTFA 2012: Conference Proceedings from the 38th International Symposium for Testing and Failure Analysis ◽

10.31399/asm.cp.istfa2012p0310 ◽

2012 ◽

Author(s):

Dongmei Meng ◽

Laura Buck ◽

James Cargo

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Corrosion Mechanism ◽

Fundamental Study ◽

Corrosion Failure ◽

Transmission Electron ◽

Intermetallic Compound Formation ◽

Scanning Transmission ◽

Low K

Abstract Cu needs a higher level of ultrasound combined with bonding force to be bonded to the Al pad properly, not just because Cu is harder than Au, but it is also harder to initiate intermetallic compounds (IMC) formation during bonding. This increases the chances of damaging the metal/low k stack under the bondpad. This paper presents a fundamental study of IMC as well as one example of a failure mode of Cu/Al bonded devices, all based on detailed analysis using scanning electron microscopy, scanning transmission electron microscopy, energy dispersive spectrometers, and transmission electron microscopy. It presents a case study showing a corrosion mechanism of Cu/Al ballbond after 168hr UHAST stress. It is observed that all Cu9Al4 was consumed, while very little copper aluminide remained after 168 hours of UHAST stressing.

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Unique Autoclave Stress Induced Failure Mechanism

ISTFA 2005: Conference Proceedings from the 31st International Symposium for Testing and Failure Analysis ◽

10.31399/asm.cp.istfa2005p0427 ◽

2005 ◽

Author(s):

John Butchko ◽

Bruce T. Gillette

Keyword(s):

Corrosion Rate ◽

Grain Boundary ◽

Failure Analysis ◽

Failure Mechanism ◽

Metal Corrosion ◽

Corrosion Mechanism ◽

Reliability Testing ◽

Process Change ◽

Transistor Reliability ◽

Pass Through

Abstract Autoclave Stress failures were encountered at the 96 hour read during transistor reliability testing. A unique metal corrosion mechanism was found during the failure analysis, which was creating a contamination path to the drain source junction, resulting in high Idss and Igss leakage. The Al(Si) top metal was oxidizing along the grain boundaries at a faster rate than at the surface. There was subsurface blistering of the Al(Si), along with the grain boundary corrosion. This blistering was creating a contamination path from the package to the Si surface. Several variations in the metal stack were evaluated to better understand the cause of the failures and to provide a process solution. The prevention of intergranular metal corrosion and subsurface blistering during autoclave testing required a materials change from Al(Si) to Al(Si)(Cu). This change resulted in a reduced corrosion rate and consequently prevented Si contamination due to blistering. The process change resulted in a successful pass through the autoclave testing.

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