Deformation and fracture of zirconium hydrides during the plastic straining of Zr-4

MRS Advances ◽  
2020 ◽  
Vol 5 (11) ◽  
pp. 559-567
Author(s):  
Luca Reali ◽  
Saïd El Chamaa ◽  
Daniel S. Balint ◽  
Catrin M. Davies ◽  
Mark R. Wenman
Keyword(s):  
Crack Nucleation ◽  
Zirconium Alloys ◽  
Temperature Deformation ◽  
Internal Stresses ◽  
Sem Images ◽  
Nucleation Sites ◽  
Deformation And Fracture ◽  
Zirconium Hydrides ◽  
Fission Reactors ◽  
Zr Alloy

ABSTRACTCrack initiation in zirconium alloys is an important issue for the safety of water-cooled fission reactors. Zirconium hydrides that precipitate in service are potential crack nucleation sites. In this work, the deformation and cracking of zirconium hydrides was studied during room temperature deformation of a Zircaloy-4 tensile sample up to fracture. The sample contained a hydrogen concentration of 100 ± 20 ppm. The main aims of this study were to better understand the mechanisms behind the hydride fracture in a polycrystalline matrix, and to identify at which point in the deformation of the Zr matrix the first hydrides break. Cracks thus nucleated may coalesce and propagate through the hydrided Zr-alloy. Scanning electron microscopy (SEM) images of a number of hydrides, both intergranular and intragranular, were taken at discrete increments of deformation during an interrupted tensile test. The results show that cracks in hydrides tend to always occur normal to the applied load, signalling the importance of the external stress. However, evidence is also provided to support the hypothesis that internal stresses generated by microstructural constraints may lead to the fracture of some intergranular hydrides.

Deformation and fracture behavior of an Al-Li-Cu-Mg-Zr alloy 8090

1990 ◽  
Vol 48 (4) ◽  
pp. 974-975
Author(s):  
D.M. Jiang ◽  
B.D. Hong
Keyword(s):  
High Strength ◽  
Deformation And Fracture ◽  
Fracture Behaviors ◽  
Aluminum Lithium ◽  
Carbon Fiber Reinforced Composites ◽  
Peak Aged ◽  
Aluminum Lithium Alloys ◽  
High Strength Aluminum Alloys ◽  
Lithium Alloys ◽  
Zr Alloy

Aluminum-lithium alloys have been recently got strong interests especially in the aircraft industry. Compared to conventional high strength aluminum alloys of the 2000 or 7000 series it is anticipated that these alloys offer a 10% increase in the stiffness and a 10% decrease in density, thus making them rather competitive to new up-coming non-metallic materials like carbon fiber reinforced composites.The object of the present paper is to evaluate the inluence of various microstructural features on the monotonic and cyclic deformation and fracture behaviors of Al-Li based alloy. The material used was 8090 alloy. After solution treated and waster quenched, the alloy was underaged (190°Clh), peak-aged (190°C24h) and overaged (150°C4h+230°C16h). The alloy in different aging condition was tensile and fatigue tested, the resultant fractures were observed in SEM. The deformation behavior was studied in TEM.

scholarly journals Selective Anisotropy of Mechanical Properties in Inconel718 Alloy

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3869
Author(s):  
Yu Liang ◽  
Jun Ma ◽  
Baogang Zhou ◽  
Wei Li
Keyword(s):  
Solid Solution ◽  
Crack Nucleation ◽  
Rolling Direction ◽  
Mechanical Anisotropy ◽  
Solution Temperature ◽  
Weak Anisotropy ◽  
Nucleation Sites ◽  
Micro Cracks ◽  
Δ Phase ◽  
Rupture Properties

Mechanical anisotropy behaviors are investigated in slightly rolled Inconel718 alloy with string-like δ phase and carbides produced during various solid-solution and aging treatments. A weak anisotropy in the strengths and rupture properties at 650 °C is visible, whereas ductility, i.e., reduction in area (RA) and impact toughness (CVN), presents a sound anisotropy behavior. MC carbides promote the operation of slip systems and thus are conducive to weakening the strength anisotropy. The RA anisotropy mainly stems from high-density δ phase particles that provide more crack nucleation sites and stimulate rapid propagation because of the shorter bridge distance between micro-cracks at the rolling direction. In contrast, CVN anisotropy arises from both δ phase and carbides at a lower solid-solution temperature of 940 °C but only depends on carbides at 980 °C where the δ phase fully dissolves. Apart from dislocation motions operated at room temperature, the activated grain boundary processes are responsible for the weak anisotropy of rupture properties at the elevated temperature. This work provides a guideline for technological applications in the hot working processes for Inconel718 alloys.

scholarly journals Mechanical properties of zirconium alloys and zirconium hydrides predicted from density functional perturbation theory

2015 ◽  
Vol 44 (43) ◽  
pp. 18769-18779 ◽  
Author(s):  
Philippe F. Weck ◽  
Eunja Kim ◽  
Veena Tikare ◽  
John A. Mitchell
Keyword(s):  
Mechanical Properties ◽  
Perturbation Theory ◽  
Elastic Properties ◽  
Density Functional ◽  
Mechanical Stability ◽  
Zirconium Alloys ◽  
Density Functional Perturbation Theory ◽  
Zirconium Hydrides

The elastic properties and mechanical stability of zirconium alloys and zirconium hydrides have been investigated within the framework of density functional perturbation theory. Results show that the lowest-energy Pn3̄m δ-ZrH1.5 phase is not mechanically stable.

Low-temperature deformation and fracture of CuNb bimetal

Cryogenics ◽  
1985 ◽  
Vol 25 (3) ◽  
pp. 146-151 ◽  
Author(s):  
V.A. Lototskaya ◽  
Yu.A. Pokhil ◽  
V.Ya. Ilichev ◽  
F.F. Lavrentev ◽  
S.P. Zabolotin
Keyword(s):  
Low Temperature ◽  
Temperature Deformation ◽  
Deformation And Fracture

Peculiarities of the Rheological Behavior for the Al-Mg-Sc-Zr Alloy Under High-Temperature Deformation

2014 ◽  
Vol 23 (12) ◽  
pp. 4271-4277 ◽  
Author(s):  
A. S. Smirnov ◽  
A. V. Konovalov ◽  
V. G. Pushin ◽  
A. N. Uksusnikov ◽  
A. A. Zvonkov ◽  
...  
Keyword(s):  
High Temperature ◽  
Rheological Behavior ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Zr Alloy

scholarly journals Regularities of Low-Temperature Deformation and Fracture of Polyimide Films of Kapton H Type of Different Thickness

2020 ◽  
Keyword(s):  
Strain Rate ◽  
Thick Film ◽  
Sharp Decrease ◽  
Rate Sensitivity ◽  
Temperature Deformation ◽  
Relative Deformation ◽  
Polyimide Films ◽  
Deformation Curves ◽  
Deformation And Fracture ◽  
First Time

The mechanical characteristics (limit of forced elasticity σforc, fracture stress σfr, relative deformation to failure εfr) of polyimide films of kapton H type under uniaxial tension conditions along the direction of drawing in the temperature range (4.2-293 K), deformation rates (10-5 - 10-3 s-1) and film thicknesses (25, 75 and 125 μm) were investigated. It is discovered, that the forced-elastic state remains for all films up to 4.2 K of all strain rates - σfors<σfr. In this case, the reserve of elasticity significantly depends on the thickness of the film with a decrease in temperature. A sharp decrease in εfr occurs in films: 125 μm thick - at 77 K, 75 μm thick - at 4.2 K. Two variants of deformation curves are possible in a 25 μm thick film at 4.2 K: with a short nonlinear stage or with a long one proceeding jumpily. The working surface of the samples that have undergone jump deformation is covered with a deformation relief, partially representing a delayed highly elastic deformation. The σfors limit is most sensitive to the strain rate. The nature of the strain rate sensitivity σfors(έ) depends on the temperature and film thickness. The change to the opposite in the character of σfors(έ) and σfr(έ) with a decrease in temperature to 4.2 K in 75 and 125 thick films was found for a first time. Change in the character of σfors(έ) is not observed in 25 μm thick film which retains the maximum reserve of elasticity at 4.2 K

A Markov Chain Fracture Model for Intergranular Crack Propagation in Polycrystalline Materials

2010 ◽  
Vol 89-91 ◽  
pp. 29-34
Author(s):  
Muhammad A. Arafin ◽  
Jerzy A. Szpunar
Keyword(s):  
Monte Carlo ◽  
Markov Chain ◽  
Crack Propagation ◽  
Intergranular Crack ◽  
Crack Nucleation ◽  
External Stress ◽  
Polycrystalline Materials ◽  
Multiple Crack ◽  
Stress Direction ◽  
Nucleation Sites

A model for intergranular damage propagation in polycrystalline materials is proposed, based on Markov Chain theory, Monte Carlo simulation and percolation concept. The model takes into account crack branching and coalescence, multiple crack nucleation sites, crack-turning etc., as well as the effect of grain boundary plane orientations with respect to the external stress direction. Both honeycomb and voronoi microstructures were utilized as the input microstructures. The effect of multiple crack nucleation sites has been found to have great influence on the crack propagation length. It has been observed that percolation threshold reported in the literature based on hexagonal microstructure is not applicable when the effect of external stress direction on the susceptibilities of grain boundaries is considered. The successful integration of voronoi algorithm with the Markov Chain and Monte Carlo simulations has opened up the possibilities of evaluating the intergranular crack propagation behaviour in a realistic manner.

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