Activation Volume Measurement Techniques: Application to Zircaloy-4

Cuniberti, A.; Picasso, A.

doi:10.1002/1521-396x(200102)183:2<373::aid-pssa373>3.0.co;2-n

Cited by 11 publications

(5 citation statements)

References 10 publications

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“…The activation volume n* can be expressed in the following form [26][27][28] n 1~{ LDG 1 =Ls~kT(L ln : e=Ls) T (8) Figure 8 shows the activation volume of S15C steel, normalised with respect to b 3 (where b is the Burgers vector of steel, 0 . 248 nm), as a function of the experimental temperature at a true strain of 0 .…”

Section: Strain Rate Effect and Activation Parametersmentioning

confidence: 86%

Dynamic compressive flow behaviour of S15C low carbon steel over wide temperature range

Lee¹,

Liu²

2005

Materials Science and Technology

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The present study utilises the compressive split Hopkinson pressure bar to investigate the dynamic flow behaviour of S15C low carbon steel at temperatures ranging from 25 to 800uC. The effects of strain rate and temperature on the mechanical response and microstructure of the metal are evaluated. The flow stress of S15C low carbon steel is found to increase with increasing strain rate and to decrease with increasing temperature. Furthermore, the material temperature sensitivity is enhanced at higher strain rates. The study determines the strain rate sensitivity parameter and the activation volume under various strain rates and temperatures. It is found that the activation energy DG* varies as a function of strain rate and temperature and attains a maximum value of 62 kJ mol -1 under the current test conditions. A Zerilli-Armstrong bcc constitutive model is applied to describe the high strain rate plastic behaviour of S15C and is shown to produce acceptable results. Microstructural examination by TEM reveals that the dislocation density and degree of dislocation tangling both increase with increasing strain rate. Additionally, TEM observations indicate that a higher strain rate reduces the size of dislocation cells. Furthermore, it is shown that the annihilation of dislocations occurs more readily at elevated temperatures. The current results provide a valuable reference for the application of S15C low carbon steel in high speed plastic forming processes.

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Section: Strain Rate Effect and Activation Parametersmentioning

confidence: 86%

Dynamic compressive flow behaviour of S15C low carbon steel over wide temperature range

Lee¹,

Liu²

2005

Materials Science and Technology

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“…The activation volume ΔV was determined from the slope of the logarithm of the ionic conductivity lnσ against pressure p in the linear high-pressure regime [23][24][25] , according to equation (1) with R = 8.314 J K -1 mol -1 and T being the measurement temperature. We acknowledge that this is a simplified form, disregarding two terms which take into account the pressure dependence of the pre-exponential factor 𝜎 0 and the jump frequency ν have minimal impact on the result.…”

Section: Determination Of the Activation Volumementioning

confidence: 99%

Effect of Uniaxial Stack Pressure on the Performance of Nanocrystalline Electrolytes and Electrode Composites for All-Solid-State Fluoride-Ion-Batteries

Chen,

Aalto,

Vanita

et al. 2023

Preprint

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If all solid-state fluoride ion batteries want to compete with existing battery technologies, significant improvements in terms of cyclic stability are necessary to fully access the high specific capacities this battery concept can provide in theory. In this study, we report the development of a high-pressure, high-temperature battery operation stand for battery cycling under inert conditions inside a glovebox. This stand was then used to investigate the effect of stack pressure on the cell performance of conversion-based as well as intercalation-based electrode materials for fluoride ion batteries. It was found that cyclic stability as well as energy efficiency is strongly increased compared to non-pressure conditions, which is assigned to sustained inter-particle contact. Thus, the cell-design must be considered carefully to be able to distinguish intrinsic material properties from percolation- and interphase-related impacts on the cell behavior. Further, the effect of pressure on the ionic conductivity of common solid fluoride ion conductors is investigated.

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“…The variation of the activation energy with the loading condition for the Al-Sc alloy can be described via the following equation [22][23][24] DG Ã~{ Tn Ã Ls=LT ð Þ :…”

Section: Strain Rate Sensitivity and Activation Energymentioning

confidence: 99%

“…where e 0 is the frequency factor, DG * is the activation energy, K b is the Boltzmann constant, and T is the absolute temperature. The variation of the activation energy with the loading condition for the Al-Sc alloy can be described via the following equation [22][23][24]…”

Section: Strain Rate Sensitivity and Activation Energymentioning

confidence: 99%

“…In the current adiabatic deformation process, the temperature rise induced by plastic deformation must be taken into account. Therefore, the temperature term T in equation ( 9) is modified to T5T 0 zDT, where T 0 is the specified experimental temperature and DT is the deformation induced temperature rise, given by DT~½0 : 9=rC p ð eT 0 s T de T , where r is the density (2?78 g cm 23 ), C p is the heat capacity (0?92 J g 21 uC 21 ), s T is the true stress, and de T is the true strain interval. The material coefficients in equation (9) are obtained by applying regressional analysis to the experimental data plotted in Fig.…”

Section: Deformation Constitutive Equationmentioning

confidence: 99%

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Effects of strain rate and temperature on dynamic mechanical behaviour and microstructural evolution in aluminium–scandium (Al–Sc) alloy

Lee¹,

Chen²

2008

Materials Science and Technology

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The present study applies a compressive split Hopkinson bar to investigate the mechanical response, microstructural evolution and fracture characteristics of an aluminium-scandium (Al-Sc) alloy at temperatures ranging from 2100 to 300uC and strain rates of 1?2610 3 , 3?2610 3 and 5?8610 3 s 21 . The relationship between the dynamic mechanical behaviour of the Al-Sc alloy and its microstructural characteristics is explored. The fracture features and microstructural evolution are observed using scanning and transmission electron microscopy techniques. The stress-strain relationships indicate that the flow stress, work hardening rate and strain rate sensitivity increase with increasing strain rate, but decrease with increasing temperature. Conversely, the activation volume and activation energy increase as the temperature increases or the strain rate decreases. Additionally, the fracture strain reduces with increasing strain rate and decreasing temperature. The Zerilli-Armstrong fcc constitutive model is used to describe the plastic deformation behaviour of the Al-Sc alloy, and the error between the predicted flow stress and the measured stress is found to be less than 5%. The fracture analysis results reveal that cracks initiate and propagate in the shear bands of the Al-Sc alloy specimens and are responsible for their ultimate failure. However, at room temperature, under a low strain rate of 1?2610 3 s 21 and at a high experimental temperature of 300uC under all three tested strain rates, the specimens do not fracture, even under large strain deformations. Scanning electron microscopy observations show that the surfaces of the fractured specimens are characterised by transgranular dimpled features, which are indicative of ductile fracture. The depth and density of these dimples are significantly influenced by the strain rate and temperature. The transmission electron microscopy structural observations show the precipitation of Al 3 Sc particles in the matrix and at the grain boundaries. These particles suppress dislocation motion and result in a strengthening effect. The transmission electron microscopy analysis also reveals that the dislocation density increases, but the dislocation cell size decreases, with increasing strain rate for a constant level of strain. However, a higher temperature causes the dislocation density to decrease, thereby increasing the dislocation cell size.

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Activation Volume Measurement Techniques: Application to Zircaloy-4

Cited by 11 publications

References 10 publications

Dynamic compressive flow behaviour of S15C low carbon steel over wide temperature range

Dynamic compressive flow behaviour of S15C low carbon steel over wide temperature range

Effect of Uniaxial Stack Pressure on the Performance of Nanocrystalline Electrolytes and Electrode Composites for All-Solid-State Fluoride-Ion-Batteries

Effects of strain rate and temperature on dynamic mechanical behaviour and microstructural evolution in aluminium–scandium (Al–Sc) alloy

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