Fatigue behavior of nanocrystalline metals and alloys

Hanlon, Timothy; Tabachnikova, E. D.; Suresh, S.

doi:10.1016/j.ijfatigue.2005.06.035

Cited by 251 publications

(141 citation statements)

References 33 publications

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“…[5] Although limited research has been conducted into the fatigue behaviors of these materials, most published studies describe work conducted with ECAE materials. [4,[6][7][8][9][10][11][12] Low-cycle fatigue testing of ECAE metals has led to the conclusion that the fatigue lives of these UFG metals are only 20 to 50 pct of their coarse grain conventional counterparts, although a recovery heat treatment of these metals increases their fatigue lives. [4] Research into monotonic properties has shown that processing methods greatly change the final mechanical properties of UFG materials, [12,13] so it is not possible to make generalized predictions regarding the fatigue behavior of all UFG materials based solely on data collected for ECAE materials.…”

Section: Ultra-fine-grain (Ufg) and Nanocrystallinementioning

confidence: 99%

Low-Cycle Fatigue of Ultra-Fine-Grained Cryomilled 5083 Aluminum Alloy

Walley

Lavernia

Gibeling

2009

Metall Mater Trans A

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The cyclic deformation behavior of cryomilled (CM) AA5083 alloys was compared to that of conventional AA5083-H131. The materials studied were a 100 pct CM alloy with a Gaussian grain size average of 315 nm and an alloy created by mixing 85 pct CM powder with 15 pct unmilled powder before consolidation to fabricate a plate with a bimodal grain size distribution with peak averages at 240 nm and 1.8 lm. Although the ultra-fine-grain (UFG) alloys exhibited considerably higher tensile strengths than those of the conventional material, the results from plastic-strain-controlled low-cycle fatigue tests demonstrate that all three materials exhibit identical fatigue lives across a range of plastic strain amplitudes. The CM materials exhibited softening during the first cycle, similar to other alloys produced by conventional powder metallurgy, followed by continual hardening to saturation before failure. The results reported in this study show that fatigue deformation in the CM material is accompanied by slight grain growth, pinning of dislocations at the grain boundaries, and grain rotation to produce macroscopic slip bands that localize strain, creating a single dominant fatigue crack. In contrast, the conventional alloy exhibits a cell structure and more diffuse fatigue damage accumulation.

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Section: Ultra-fine-grain (Ufg) and Nanocrystallinementioning

confidence: 99%

Low-Cycle Fatigue of Ultra-Fine-Grained Cryomilled 5083 Aluminum Alloy

Walley

Lavernia

Gibeling

2009

Metall Mater Trans A

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“…[3][4][5][6][7][8][9] Indeed, published literature on the fatigue performance of NC metals clearly demonstrates improvements in fatigue strength over CG metals. [10][11][12][13][14][15] Aside from quantitative improvements in fatigue performance, NC metals also hold the possibility of new insight into the mechanisms responsible for traditional fatigue failure. In the recent past, studies on the monotonic strength of NC metals have not only revealed quantitative details regarding the Hall-Petch strengthening effect, [16][17][18] but also led to the discovery of mechanistic transitions in dislocation behavior.…”

Section: Introductionmentioning

confidence: 99%

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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“…For example, Hanlon et al [11,12] investigated the fatigue properties of nc and ufg electrodeposited Ni. Their results indicated that, with grain refinement, the resistance to subcritical fatigue fracture decreased.…”

mentioning

confidence: 99%

“…Therefore, the propagation path of the fatigue crack changed with the orientation of the grains at the front of the crack tip for cg Ni, but not for nc Ni. In the work of Hanlon et al [12], a crack deflection model was used to rationalize the decrease in fatigue crack growth rate in coarser grained samples. However, this is not sufficient.…”

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confidence: 99%

Shear bands at the fatigue crack tip of nanocrystalline nickel

Xie

Hong

2007

Scripta Materialia

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Fatigue crack growth rates in electrodeposited nanocrystalline Ni and its coarse counterpart were experimentally investigated in this paper. The shear bands, called the epsilon plastic zone, were observed on the surface of nanocrystalline Ni samples. The length of the shear bands is close to the estimated size of the plastic zone at the crack tip. Atomic force microscopy measurements indicate that the shear strain in the shear bands and the width of shear bands increase with related crack length.

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Fatigue behavior of nanocrystalline metals and alloys

Cited by 251 publications

References 33 publications

Low-Cycle Fatigue of Ultra-Fine-Grained Cryomilled 5083 Aluminum Alloy

Low-Cycle Fatigue of Ultra-Fine-Grained Cryomilled 5083 Aluminum Alloy

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

Shear bands at the fatigue crack tip of nanocrystalline nickel

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