Stress-induced movement of crystal boundaries

Li, Choh Hsien; Edwards, Eugene H.; Washburn, J.; Parker, E.R.

doi:10.1016/0001-6160(53)90062-5

Cited by 154 publications

(91 citation statements)

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“…Stress-driven boundary motion has been observed experimentally, [29][30][31]50,53,54] as well as predicted by simulations [33,34] and theory. [55] Recent experimental results by Rupert et al [30] confirmed much of this theory in NC aluminum, although for monotonic tensile stresses.…”

Section: A Adiffusional Grain Growthsupporting

confidence: 67%

Anomalous Fatigue Behavior and Fatigue-Induced Grain Growth in Nanocrystalline Nickel Alloys

Boyce

Padilla

2011

Metall Mater Trans A

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Fatigue failure due to repetitive loading of metallic devices is a pervasive engineering concern. The present work reveals extraordinary fatigue resistance in nanocrystalline (NC) alloys, which appears to be associated with the small (<100 nm) grain size inhibiting traditional cyclic damage processes. In this study, we examine the fatigue performance of three electrodeposited NC Nibased metals: Ni, Ni-0.5Mn, and Ni-22Fe (PERMALLOY). When subjected to fatigue stresses at and above the tensile yield strength where conventional coarse-grained (CG) counterparts undergo low-cycle fatigue failure (<10 4 cycles to failure), these alloys exhibit exceptional fatigue lives (in some cases, >10 7 cycles to failure). Postmortem examinations show that failed samples contain an aggregate of coarsened grains at the crack initiation site. The experimental data and accompanying microscopy suggest that the NC matrix undergoes abnormal grain growth during cyclic loading, allowing dislocation activity to persist over length scales necessary to initiate a fatigue crack by traditional fatigue mechanisms. Thus, the present observations demonstrate anomalous fatigue behavior in two regards: (1) quantitatively anomalous when considering the extremely high stress levels needed to drive fatigue failure and (2) mechanistically anomalous in light of the grain growth process that appears to be a necessary precursor to crack initiation.

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Section: A Adiffusional Grain Growthsupporting

confidence: 67%

Anomalous Fatigue Behavior and Fatigue-Induced Grain Growth in Nanocrystalline Nickel Alloys

Boyce

Padilla

2011

Metall Mater Trans A

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“…i v) The stress level on the reverse motion is initially sharply reduced, when compared with., the level before the reversal. This phenomenon which is similar to Bauschinger effect (8) was also observed in the earlier report (2). v) The stress levels for ~he initial jump are higher in alloy crystals than in pure crystals but a quantitative trend could not be established as a function of solute content due to the wide scatter in the data.…”

Section: Introductionsupporting

confidence: 84%

“…The stress-induced movement of low-angle tilt boundaries has bee9 observed in single • crystals of zinc by several investigators (1)(2)(3)(4)(5)(6). The motion o,f the.…”

Section: Introductionmentioning

confidence: 98%

Effect of solute atoms on the motion of a low angle tilt boundary

Syn

Ahmadieh²,

Morris

1975

Scripta Metallurgica

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IntroductionThe stress-induced movement of low-angle tilt boundaries has bee9 observed in single • crystals of zinc by several investigators (1-6). The motion o,f the. boundary under the action of a sheer stress in the direction of the Burgers vector of the dislocations comprising the boundary is well established. However the reported modes of the boundary motion are different from one invest'igation to another. Bainbridge et al. (3) have obse.rved that the movement at room temperature was jerky and during each jlUIIp the boundary moved through an appreciable volume of the material while Vreeland (4) reports a smooth and continuous motion at the same temperature. One would probably attribute this discrepancy to the different levels of impurity content. Zinc· crystals of 99.99 wt% p_uri_ty were used in the former investigation while crystals of higher purity (99.999 wt%) and zone refined zinc were used in the latter. Thus we decided to examine this point further by introducing much higher doses of substitutional solute atoms into the crystals. We used alloy crystals containing controlled amounts of silver as an alloying element in addition to high purity zinc crystals. ·Experimental Single crystals of high purity zinc (99.999+ wt%) and alloys containing 0.05, 0.10 and 0. 21 wt% silver. were grown in a graphite mold under helium atmosphere by a modified Bridgman technique at a rate of 0.4 em/hr.· The crystals we!e rectangular 1.3 em x 0.7 em and 8 em long and were orient-ed in the direction [1120] with their basal planes parailel to the wider faces. The side faces were parallel to the prismatic planes. In the case of alloy crystals,· a reservoir was designed in the upper portion of the mold (7) to reduce the concentration gradient along the 8 em length to about ±3%. The top parts were removed by spark cutting and the samples were cut to 2.5 em length by an acid sawing technique. Then the fol.lowing sequence of preparation and annealing under He atmosphere was applied: i) 1-hr. anneal at 400°C and furnace cool; ii) side surfaces were acid polished; iii) cleaved along the basal plane to reveal the natural surface of this plane; iv) 1-hr. anneal at 400°C and furnace cool; v) ~2° angle tilt boundary (FIG. 1) introduced by bending at room temperature; vi) 1-hr. anneal at 400°C and furnace cooled to 200°C; 2. vii) 48..:hr. aging at 200°C followed by air quench and then stored in liquid nitrogen for testing.The cleaved specimens were 2.5 em long, "-0~8 em wide and 0.2 to 0.4 em ~hick. The width and thickness could not be controlled very closely due to the difficulty of cleaving the acid polishing.The observation of the boundary motion was performed by using essentially the same r technique and stressing apparatus as used by Bainbridge et al. (3). The displacements of the Further movement starts with a jumping motion at a discontinuously increased stress level.However the motion at room temperature is different and the original position does not impose an increased stress. This phenomenon was not obserlled in the earlie...

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“…It is suggested that the grain rotation is a significant factor only for very small grains and at very high temperatures 1 , and the growth mechanism is associated with gradual GB dissociation caused by dislocation motion 15,16 . For GB migration, the motion of a low-angle GB (LAGB) is generally related to the collective motion of the individual dislocations in these boundaries [17][18][19][20] , while the migration of a high-angle GB (HAGB) is mainly described by the shuffling model 21 , the DSC (displacement shift complete) model [22][23][24] and the shear coupling models 13,25,26 . In the DSC model, the HAGB migration is attributed to the motion of the secondary GB dislocations, which result in a combined GB migration and sliding 27 .…”

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confidence: 99%

Nanotwin-assisted grain growth in nanocrystalline gold films under cyclic loading

2014

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Under mechanical loading, nanocrystalline metals show unique behaviour, among the most common of which are high strength, mechanically induced grain growth and twin formation. However, mechanically induced grain growth is seldom correlated with twins. Here we report a clear relationship between grain growth and nanoscale twins in 20-nm-thick gold films with a grain size of B19 nm under cyclic loading based on atomic-scale observations and analyses. We find that the formation of nanotwins is an effective way to assist grain coarsening, following a fundamental process that the mutual formation of nanotwins in two neighbouring grains changes the local grain orientation and dissociates the grain boundary into new segments, which become more mobile. The proposed mechanism of nanotwin-assisted grain growth may have important implications for understanding the interface-mediated mechanisms of cyclic plastic deformation and for the interface engineering design of nanostructured metals with both high strength and good fatigue resistance.

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Stress-induced movement of crystal boundaries

Cited by 154 publications

References 1 publication

Anomalous Fatigue Behavior and Fatigue-Induced Grain Growth in Nanocrystalline Nickel Alloys

Anomalous Fatigue Behavior and Fatigue-Induced Grain Growth in Nanocrystalline Nickel Alloys

Effect of solute atoms on the motion of a low angle tilt boundary

Nanotwin-assisted grain growth in nanocrystalline gold films under cyclic loading

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