High Temperature Nanomechanical Testing

Monclús, M.A.; Molina-Aldareguía, J.M.

doi:10.1007/978-981-10-6855-3_55-1

Cited by 8 publications

(6 citation statements)

References 76 publications

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“…Here, the Burgers vector (b) for the FCC alloys was calculated as b = 1/2a 0 [110], where a 0 is the lattice parameter with values of 0.352 nm, 0.3567 nm and 0.3597 nm for Ni, CoCrNi, and CoCrFeMnNi, respectively [35,44]. V* in the range of 100b 3 -1000b 3 is associated with dislocation interaction mechanism and in the range of 10b 3 -100b 3 with dislocation glide [45]. Therefore, the obtained activation volume for Ni was in the range for dislocation interaction while the lower value of V* for the two MPEAs indicates dislocation glide mechanism.…”

Section: Discussionmentioning

confidence: 99%

High-Temperature Nano-Indentation Creep Behavior of Multi-Principal Element Alloys under Static and Dynamic Loads

Sadeghilaridjani

Mukherjee

2020

Metals

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Creep is a serious concern reducing the efficiency and service life of components in various structural applications. Multi-principal element alloys are attractive as a new generation of structural materials due to their desirable elevated temperature mechanical properties. Here, time-dependent plastic deformation behavior of two multi-principal element alloys, CoCrNi and CoCrFeMnNi, was investigated using nano-indentation technique over the temperature range of 298 K to 573 K under static and dynamic loads with applied load up to 1000 mN. The stress exponent was determined to be in the range of 15 to 135 indicating dislocation creep as the dominant mechanism. The activation volume was ~25b3 for both CoCrNi and CoCrFeMnNi alloys, which is in the range indicating dislocation glide. The stress exponent increased with increasing indentation depth due to higher density and entanglement of dislocations, and decreased with increasing temperature owing to thermally activated dislocations. The results for the two multi-principal element alloys were compared with pure Ni. CoCrNi showed the smallest creep displacement and the highest activation energy among the three systems studied indicating its superior creep resistance.

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Section: Discussionmentioning

confidence: 99%

High-Temperature Nano-Indentation Creep Behavior of Multi-Principal Element Alloys under Static and Dynamic Loads

Sadeghilaridjani

Mukherjee

2020

Metals

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“…Large stress reductions at the beginning of the CCP segment lead to a sharp drop in the activation volume. In the low stress regime, V values of 2 -7 b³ where derived for Cu-X and 2 -3 b³ for Ni20 and Ni100, indicating dislocation annihilation and grain boundary mediated processes become dominant [47,48].…”

Section: Deformation Mechanismsmentioning

confidence: 95%

“…Activation volumes of 19-33 b³ (Cu-IOP Publishing doi:10.1088/1757-899X/1249/1/012003 10 X) or 17-20 b³ (Ni-X) were determined in the high stress regime. In literature, activation volumes of 10-100 b³ are discussed for dislocation-glide based plasticity (dislocation nucleation and/or dislocation cross-slip [25,[46][47][48]. Large stress reductions at the beginning of the CCP segment lead to a sharp drop in the activation volume.…”

Section: Deformation Mechanismsmentioning

confidence: 99%

Solid solution hardening effects on structure evolution and mechanical properties of nanostructured binary and high entropy alloys after high pressure torsion

Keil

Minnert²,

Bruder³

et al. 2022

IOP Conf. Ser.: Mater. Sci. Eng.

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Two different alloy series (Cu-X, Ni-X) have been selected to investigate the effects of solutes on the saturation grain size, the thermal stability and mechanical properties after high pressure torsion. The results of the Cu-X series indicate that the saturation grain size does not correlate with the stacking fault energy but shows good agreement with solid solution hardening according to the Labusch model. This correlation does not only hold for binaries, but also for chemically complex high entropy alloys (Ni-X) in the form of (CrMnFeCo)xNi1-x, where the Varvenne model is used to describe solid solution hardening. The alloy series exhibit a grain size in the range of 50 – 425 nm after high pressure torsion and the solutes increase the strength as well as the thermal stability of the alloys after annealing. The nanostructured alloys exhibit an enhanced strain rate sensitivity exponent, as determined from nanoindentation strain rate jump and constant contact pressure creep testing, whereas an enhanced rate sensitivity is found at low strain rates. The relatively lower rate sensitivity of the alloys as well as their higher thermal stability indicate, that defect storage and annihilation is strongly influenced by a complex interaction of solutes, dislocations and grain boundaries.

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“…This allows testing relevant technological materials under real operating conditions, widening the applicability of these techniques to important industrial applications, such as the hard-coating industry, high temperature metallic alloys, and corrosion layers, etc. (12,13). The major difficulties faced when testing under non-ambient temperature conditions are instrument stability, accounting for thermal gradients, management of thermal drift, and chemical stability, not only of the specimen itself, but also of the indenter tip material.…”

Section: High and Low Temperaturesmentioning

confidence: 99%