Effects of precipitates and dislocation loops on the yield stress of irradiated iron

Lehtinen, Arttu; Laurson, Lasse; Granberg, Fredric; Nordlund, K.; Alava, Mikko J.

doi:10.1038/s41598-018-25285-z

Cited by 61 publications

(19 citation statements)

References 52 publications

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“…Also important is that one uses (2r p ρ p ) −1/2 as the mean interprecipitate distance in the glide plane (inset of Fig. 3) [29] as a measure of the true interaction range. Thus…”

Section: Plastic Flow Under Constant Stressmentioning

confidence: 99%

“…To this end, we study how small, randomly distributed spherical obstacles of different dislocation-precipitate interaction strengths A and densities ρ p affect the collective dislocation dynamics in fcc aluminum single crystals. This is done by extensive 3D DDD simulations utilizing our recently developed methodology [28,29] to include coherent precipitates with short-range elastic interactions with the dislocations [28][29][30]. We consider dislocation networks under both quasistatically increasing stress and constant loading, as illustrated in Fig.…”

Section: Introductionmentioning

confidence: 99%

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Plastic yielding and deformation bursts in the presence of disorder from coherent precipitates

Salmenjoki

Lehtinen

Laurson

et al. 2020

Phys. Rev. Materials

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Alloying metals with other elements is often done to improve the material strength or hardness. A key microscopic mechanism is precipitation hardening, where precipitates impede dislocation motion, but the role of such obstacles in determining the nature of collective dislocation dynamics remains to be understood. Here, three-dimensional discrete dislocation dynamics simulations of fcc single crystals are performed with fully coherent spherical precipitates from zero precipitate density up to ρ p = 10 21 m −3 and at various dislocationprecipitate interaction strengths. When the dislocation-precipitate interactions do not play a major role, the yielding is qualitatively the same as for pure crystals, i.e., dominated by "dislocation jamming," resulting in glassy dislocation dynamics exhibiting critical features at any stress value. We demonstrate that increasing the precipitate density and/or the dislocation-precipitate interaction strength creates a true yield or dislocation assembly depinning transition, with a critical yield stress. This is clearly visible in the statistics of dislocation avalanches observed when quasistatically ramping up the external stress, and it is also manifested in the response of the system to constant applied stresses. The scaling of the yielding with precipitates is discussed in terms of the Bacon-Kocks-Scattergood relation.

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“…Also important is that one uses (2r p ρ p ) −1/2 as the mean interprecipitate distance in the glide plane (inset of Fig. 3) [29] as a measure of the true interaction range. Thus…”

Section: Plastic Flow Under Constant Stressmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Plastic yielding and deformation bursts in the presence of disorder from coherent precipitates

Salmenjoki

Lehtinen

Laurson

et al. 2020

Phys. Rev. Materials

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“…Nevertheless, it would be interesting to extend the present study to consider the predictability of depinning dynamics in such systems. Finally, we point out two crucial outstanding questions related to deformation predictability: The problem remains to be addressed in realistic three-dimensional DDD simulations, with 28,42 or without 25 additional defects interfering with dislocation motion, as well as in experiments where descriptors of the initial sample microstructure could be extracted, e.g., by X-ray measurement techniques. [43][44][45]…”

Section: Discussionmentioning

confidence: 99%

Machine learning depinning of dislocation pileups

Sarvilahti,

Skaugen,

Laurson

2020

Preprint

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We study a one-dimensional model of a dislocation pileup driven by an external stress and interacting with random quenched disorder, focusing on predictability of the plastic deformation process. Upon quasistatically ramping up the externally applied stress from zero the system responds by exhibiting an irregular stress-strain curve consisting of a sequence of strain bursts, i.e., critical-like dislocation avalanches. The strain bursts are power-law distributed up to a cutoff scale which increases with the stress level up to a critical flow stress value. There, the system undergoes a depinning phase transition and the dislocations start moving indefinitely, i.e., the strain burst size diverges. Using sample-specific information about the pinning landscape as well as the initial dislocation configuration as input, we employ predictive models such as linear regression, simple neural networks and convolutional neural networks to study the predictability of the simulated stress-strain curves of individual samples. Our results show that the response of the system -including the flow stress value -can be predicted quite well, with the correlation coefficient between predicted and actual stress exhibiting a non-monotonic dependence on strain. We also discuss our attempts to predict the individual strain bursts.

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“…Also important is that one uses (2r p ρ p ) −1/2 as the mean inter-precipitate distance in the glide plane (Inset of Fig. 3) [29] as a measure of the true interaction range. Thus…”

Section: Plastic Flow Under Constant Stressmentioning

confidence: 99%

Plastic yielding and deformation bursts in the presence of disorder from coherent precipitates

Salmenjoki,

Lehtinen,

Laurson

et al. 2020

Preprint

Self Cite

View full text Add to dashboard Cite

Alloying metals with other elements is often done to improve the material strength or hardness.A key microscopic mechanism is precipitation hardening, where precipitates impede dislocation motion, but the role of such obstacles in determining the nature of collective dislocation dynamics remains to be understood. Here, three-dimensional discrete dislocation dynamics simulations of FCC single crystals are performed with fully coherent spherical precipitates from zero precipitate density upto ρp = 10 21 m −3 and at various dislocation-precipitate interaction strengths. When the dislocation-precipitate interactions do not play a major role the yielding is qualitatively as for pure crystals, i.e., dominated by "dislocation jamming", resulting in glassy dislocation dynamics exhibiting critical features at any stress value. We demonstrate that increasing the precipitate density and/or the dislocation-precipitate interaction strength creates a true yield or dislocation assembly depinning transition, with a critical yield stress. This is clearly visible in the statistics of dislocation avalanches observed when quasistatically ramping up the external stress, and is also manifested in the response of the system to constant applied stresses. The scaling of the yielding with precipitates is discussed in terms of the Bacon-Kocks-Scattergood relation.

show abstract

Effects of precipitates and dislocation loops on the yield stress of irradiated iron

Cited by 61 publications

References 52 publications

Plastic yielding and deformation bursts in the presence of disorder from coherent precipitates

Plastic yielding and deformation bursts in the presence of disorder from coherent precipitates

Machine learning depinning of dislocation pileups

Plastic yielding and deformation bursts in the presence of disorder from coherent precipitates

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