Nanoindentation creep behavior of coarse-grained and ultrafine-grained pure magnesium and AZ31 alloy

Hu, Jiangjiang; Zhang, Wei; Bi, Guangli; Lu, Jiping; Huo, Wangtu; Zhang, Yusheng

doi:10.1016/j.msea.2017.05.063

Cited by 35 publications

(8 citation statements)

References 35 publications

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“…Accordingly, the higher the LSR, the more the stored dislocations, and consequently, the larger the creep displacements during the holding stage. This model well explains the normal strain rate dependence of indentation creep displacements in previous studies on CG and NC materials [17,42,71]. In the present work, with increasing LSR, twinning activities are enhanced, generating more twin boundaries.…”

Section: Negative Strain Rate Dependence Of Creep Displacementsupporting

confidence: 89%

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Twinning-Induced Abnormal Strain Rate Sensitivity and Indentation Creep Behavior in Nanocrystalline Mg Alloy

Wan

Liu

et al. 2021

Materials

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Nanocrystalline materials exhibit many unique physical and chemical properties with respect to their coarse-grained counterparts due to the high volume fraction of grain boundaries. Research interests on nanocrystalline materials around the world have been lasting over the past decades. In this study, we explored the room temperature strain rate sensitivity and creep behavior of the nanocrystalline Mg–Gd–Y–Zr alloy by using a nanoindentation technique. Results showed that the hardness and creep displacements of the nanocrystalline Mg–Gd–Y–Zr alloy decreased with increasing loading strain rate. That is, the nanocrystalline Mg–Gd–Y–Zr alloy showed negative strain rate sensitivity and its creep behavior also exhibited negative rate dependence. It was revealed that the enhanced twinning activities at higher loading strain rates resulted in reduced hardness and creep displacements. The dominant creep mechanism of the nanocrystalline Mg–Gd–Y–Zr alloy is discussed based on a work-of-indentation theory in this paper.

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Section: Negative Strain Rate Dependence Of Creep Displacementsupporting

confidence: 89%

“…A nanoindentation test is an effective and high-efficiency method to characterize the SRS and creep behaviors of NC materials [41,42]. Here, we explored the room temperature SRS and indentation creep behavior of a NC Mg-Gd-Y-Zr alloy by using a nanoindentation technique.…”

Section: Introductionmentioning

confidence: 99%

Twinning-Induced Abnormal Strain Rate Sensitivity and Indentation Creep Behavior in Nanocrystalline Mg Alloy

Wan

Liu

et al. 2021

Materials

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“…Many studies have reported that introducing a larger volume of the GB structure could enhance m values in NC metals, such as NC Ni [16,19], NC Cu [14][15][16], nanotwinned Cu [20], NC Ta [21], and NC Mg [22]. The rate sensitivity of the mechanical properties is related to the thermally activated process of overcoming the obstacles of the glissile dislocation movement, which are normally expressed by the activation volume (v) of the thermally activated event.…”

Section: Discussionmentioning

confidence: 99%

“…Besides that, because of the limited intragranular space and GB activities such as GB sliding and rotation in NC metals, dislocation gliding occurs only on fewer slip systems and high stress concentration created in some local regions such as triple junctions would relax, which could reduce the number of the dislocations and further weaken pile-up lateral extension around the imprints. As the grain size enters the ranges of 100-1500 nm, although a number of GB mechanisms such as GB sliding and GB rotation would participate in their plastic deformation, the transition between intragranular and intergranular deformation mechanism is not supposed to be abrupt [14,16,19,21,22,24]. Dislocation activities such as the cross-and multiple-slips from the internal source can still be activated effectively in the large grain zones, and dislocations can be trapped inside the grains as a result of dislocation interactions between slip systems or with debris left by cross-slip.…”

Section: Discussionmentioning

confidence: 99%

Nanoindentation-Induced Pile-Up in the Residual Impression of Crystalline Cu with Different Grain Size

Zhang

Sun

et al. 2017

Crystals

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Nanoindentation morphologies of crystalline copper have been probed at the grain scale. Experimental tests have been conducted on nanocrystalline (NC), ultrafine-grained (UFG), and coarse-grained (CG) copper samples with a new Berkvoich indenter at the strain rate of 0.04/s without holding time at an indentation depth of 2000 nm at room temperature. As the grain size increases, the height of the pile-up around the residual indentation increases and then exhibits a slightly decrease in the CG Cu. The maximum of the pile-up in the CG Cu obviously deviates from the center of the indenter sides. Our analysis has revealed that the dislocation motion and GB activities in the NC Cu, some cross-and multiple-slip dislocations inside the larger grain in the UFG Cu, and forest dislocations from the intragranular Frank-Read sources in the CG Cu would directly induce this distinct pile-up effect.

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“…Grain size (d) refinement is a well-known strengthening mechanism for improving the mechanical properties of metallic materials [1][2][3][4][5][6][7]. In particular, materials with ultrafine/nano grain size often possess a higher strength compared with their coarse-grained (CG) counterparts.…”

Section: Introductionmentioning

confidence: 99%

Softening Behaviors of Severely Deformed Zn Alloy Studied by the Nanoindentation

Zhang

Peng

et al. 2020

Coatings

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Zamak 3 alloy treatment by sliding-friction treatment (SFT) was investigated by nanoindentation to explore the influence of microstructure and strain rate on nanoscale deformation at room temperature. The results show that obvious material softening occurs in the ultrafine-grained (UFG) Zn alloy and strain-hardening happens in the twinning-deformed layer, respectively. It can be concluded that almost constant values of V in the UFG Zn alloy contribute to the dislocations moving along the grain boundary (GB) not cross the grain interior. In the twinning-deformed layer, the highly frequent dislocation–twinning boundary (TB) interactions are responsible for subsequent inverse Cottrell–Stokes at lower stress, which is quite different from dislocation–dislocation reaction inside the grain in their coarse-grained (CG) counterpart.

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Nanoindentation creep behavior of coarse-grained and ultrafine-grained pure magnesium and AZ31 alloy

Cited by 35 publications

References 35 publications

Twinning-Induced Abnormal Strain Rate Sensitivity and Indentation Creep Behavior in Nanocrystalline Mg Alloy

Twinning-Induced Abnormal Strain Rate Sensitivity and Indentation Creep Behavior in Nanocrystalline Mg Alloy

Nanoindentation-Induced Pile-Up in the Residual Impression of Crystalline Cu with Different Grain Size

Softening Behaviors of Severely Deformed Zn Alloy Studied by the Nanoindentation

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