Theoretical Evidence for the Single-Ended-Source Controlled Yield Strengths of Micropillar FCC and BCC Metal Single Crystals

Takeuchi, Shin; Kamimura, Yoshihiro; Edagawa, Keiichi

doi:10.2320/matertrans.mt-m2021137

Cited by 3 publications

(1 citation statement)

References 42 publications

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“…2) could contribute to the variation in size-dependent strength by the cold-rolling. In general, the mechanism of size-dependent strength for the single crystals of metals was rationalized by truncation of single-arm dislocation sources 10,2224) or exhaustion/starvation of dislocation sources. 25,30,31) Assuming the pre-existing dislocations were homogenously distributed within the experimental single crystals, the stochastic model of the dislocation source length (proposed by Parthasarathy et al 22) ) could be applied to describe the size dependence of strength.…”

Section: Size-dependent Strength Based On the Stochastic Model Of Dis...mentioning

confidence: 99%

Influence of Dislocation Substructure on Size-Dependent Strength of High-Purity Aluminum Single-Crystal Micropillars

et al. 2023

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In order to understand the influence of dislocation substructures on the size-dependent strength (smaller is stronger) of micron-sized metals, we have fabricated single-crystal cylindrical micropillars with various diameters approximately ranging from 1 to 10 µm, which were prepared on the surface of the fully annealed sample and the subsequently cold-rolled samples of high-purity aluminum (Al). The annealed micropillars exhibited a size dependence of the resolved shear stress required for slip. The shear stress (¸i) normalized by shear modulus (G) and the specimen diameter (d) normalized by Burgers vector (b) followed the correlation of ¸i/G = 0.33(d/b) ¹0.63 . The size-dependent strength was reduced by cold-rolling, resulting in lower power-law exponents (0.26³0.31) for the correlation in the cold-rolled specimens. The fine dislocation substructures introduced by the cold-rolling could be associated with the reduced size-dependent strength, which can be rationalized using the stochastic model of the dislocation source length in an assumption of homogenously distributed dislocations existing in the experimental micropillars. The inhomogeneous dislocation substructure with various dislocation cell sizes would contribute to a variation in the measured strength depending on the location, likely due to the probability of exiting the dislocation cell walls (local variation in dislocation density) in the micropillars fabricated on the cold-rolled Al samples.

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Section: Size-dependent Strength Based On the Stochastic Model Of Dis...mentioning

confidence: 99%

Influence of Dislocation Substructure on Size-Dependent Strength of High-Purity Aluminum Single-Crystal Micropillars

et al. 2023

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Experimental Guides for Metallic Materials 2. Measurement and Evaluation of Material Properties 2-1 Mechanical Properties 2-1-4 Compression Test (incl. Micropillar Compression)

Kishida

2023

Materia Japan

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単結晶マイクロピラー圧縮試験を用いたAl-Fe合金積層造形体の高強度支配因子の検討

Choshi,

Zhu,

Takata

et al. 2023

J.JILM

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In this study, we aim to address the dominant microstructural parameter of the high strength of Al-Fe alloy components additive-manufactured by the laser powder bed fusion (L-PBF) process. This study systematically investigated the compression response of single-crystal micropillars with a fixed diameter of approximately 3 μm prepared on the surfaces of the L-PBF built Al-2.5%Fe binary alloy sample, and the subsequently heat-treated samples (300°C and 500°C), together with the slowly solidified Al-2.5%Fe alloy sample for comparison. The single-crystal micropillars of the L-PBF built sample exhibited a high yield strength of approximately 250 MPa and pronounced strain hardening. The compressed single-crystal specimens exhibited a uniform deformation indicating the activated multi-slip systems. Such a trend was observed in the 300°C heat-treated sample. However, the relatively low yield strength and strain hardening rate were found in single-crystal micropillars of the 500°C heat-treated sample as well as the slowly solidified sample. In the compressed micropillars, a single-slip system was dominantly activated. These results indicated that numerous nano-sized Al 6 Fe-phase particles (contained in the specimens of the L-PBF built sample and the 300°C heat-treated sample) could contribute to high yield strength and the enhanced activation of multi-slip systems resulting in the pronounced strain hardening.

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Theoretical Evidence for the Single-Ended-Source Controlled Yield Strengths of Micropillar FCC and BCC Metal Single Crystals

Cited by 3 publications

References 42 publications

Influence of Dislocation Substructure on Size-Dependent Strength of High-Purity Aluminum Single-Crystal Micropillars

Influence of Dislocation Substructure on Size-Dependent Strength of High-Purity Aluminum Single-Crystal Micropillars

Experimental Guides for Metallic Materials 2. Measurement and Evaluation of Material Properties 2-1 Mechanical Properties 2-1-4 Compression Test (incl. Micropillar Compression)

単結晶マイクロピラー圧縮試験を用いたAl-Fe合金積層造形体の高強度支配因子の検討

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