Slip planes and asymmetric slip in fatigue of iron single crystals

Nine, Harmon D.

doi:10.1080/14786437208220351

Cited by 31 publications

(8 citation statements)

References 15 publications

(1 reference statement)

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“…In a study on a-iron single crystals fatigued in torsion, Nine [36] concluded that the observed slip planes were different for forward and reverse shear deformations. Similar effects of slip plane asymmetry have been observed on a-iron [7] and also on 202 H. Mughrabi et al niobium [37][38][39] single crystals in push-pull fatigue experiments at constant Ae~t.…”

Section: Asymmetric Slip and Shape Changesmentioning

confidence: 99%

“…For similar values of e, ..... the shape changes are small at low Aepl (no shape changes could be detected for Aeot = 10 4) and increase considerably with increasing Ae~t up to Aept-5 × 10 -3, Beyond this amplitude the dependence on Aept becomes negligible. Since the asymmetric slip which is responsible for the shape changes [7,[36][37][38] stems from the non-equivalence of forward and reverse glide of the screw dislocations, it can be concluded from Fig. 5 that the screw dislocations perform only small displacements in the range of cyclic microstrains of some 10 -4 but glide more extensively as Ae~ approaches values characteristic of cyclic macrostrains (-5 × 10 3).…”

Section: Asymmetric Slip and Shape Changesmentioning

confidence: 99%

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Cyclic deformation and fatigue behaviour of ?-iron mono-and polycrystals

1981

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strongly impeded dislocation multiplication below Aept -5 × 10 -4, appreciable secondary slip at higher Aepl leading to a cell structure (persistent slip bands do not form), shape changes due to asymmetric slip of screw dislocations and a relatively high effective stress level.The reduction of ~p~ and the presence of solute carbon atoms modify this behaviour significantly, making it more similar to that of f.c.c, metals. In all cases it was found that only the athermal component of the peak (saturation) stress but not the latter itself represents a suitable measure of the properties of the dislocation substructure.On the basis of the cyclic deformation behaviour and of observations of trans-and intergranular fatigue crack initiation it was concluded that the fatigue limit of a-iron is an intrinsic property of the b.c.c. structure whose characteristics, however, are affected sensitively by interstitial impurity content and by the strain rate of the fatigue test.

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Section: Asymmetric Slip and Shape Changesmentioning

confidence: 99%

Section: Asymmetric Slip and Shape Changesmentioning

confidence: 99%

Cyclic deformation and fatigue behaviour of ?-iron mono-and polycrystals

1981

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“…At medium and high-temperatures, effective slip on f112g planes has been observed experimentally in all bcc metals (W [8], Mo [9], Ta [10], and Nb [11]). Slip on f123g planes has also been reported in W and Mo [7] and in a-Fe [12].…”

Section: Introductionmentioning

confidence: 80%

“…Such an uniaxial deformation experiment in which f112g or f123g slip systems are expected to be active should be conducted in an orientation close to one of the corners of the [001]-[011]-½ " 111 stereographic triangle since the Schmid factors of the f112g and f123g slip systems are higher there than the Schmid factor of the most favorable f110g slip system. The experiment should furthermore be conducted at medium or high temperatures because in this regime macroscopic f112g [5,17] and f123g slip [7,12,37] have been observed in several bcc metals. It must be emphasized that demonstrating the occurrence of even a single b ¼ ah100i junction along another direction than the h100i or h111i directions (Fig.…”

Section: Discussionmentioning

confidence: 99%

Dislocation junctions as indicators of elementary slip planes in body-centered cubic metals

2014

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In body-centered cubic (bcc) metals, an unambiguous determination of the elementary slip planes remains difficult owing to several possible interpretations of the glide activity, of slip steps on the specimen surface or features of the dislocation microstructure. In this article, a method is proposed to determine the elementary slip planes in bcc metals based on the line directions of sessile junctions resulting from the interaction of mobile dislocations with (Formula presented.) Burgers vector. The proposed method allows to determine slip activity inside a material and not at its surface, where other effects may play a role. It is in principle applicable to determining the elementary slip plane in any crystalline material. Particularly, it may help to resolve a long-standing debate of the nature of the elementary slip planes in bcc metals

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“…Cyclic creep can also be found in cases where there is no mean stress but there is an anisotropy in the yield point in tension and compression for the material. This yield point anisotropy which leads to asymmetric deformation is seen in many of the bcc metals [4][5][6][7]. It is now accepted that the stress asymmetry is due to the glide stress on dissociation of 1/2<111> dislocations into 116<111> partial dislocations and their core configurations at temperatures below 0.…”

Section: Methodsmentioning

confidence: 99%

Thermal Fatigue of NiAl Single Crystals

1998

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Single crystals of [001)-oriented NiAI single crystals were subjected to thermal fatigue by a method which employs induction heating of disk-shaped specimens heated in an argon atmosphere. Several time-temperature heating and cooling profiles were used to produce different thermal strain histories in specimens cycled between 973 K and 1473 K. After thermal cycling, pronounced shape changes in the form of diametrical elongations along <100> directions with accompanying increases in thickness at and near the <100> specimen axes were observed. The deformations were analyzed in terms of operative slip systems in tension and compression, ratchetting (cyclic strain accumulation), and the elastic properties of NiAl. The experimental results correlate best with thermal stresses associated with the large elastic anisotropy of NiAl. INTRODUCTIONOrdered intermetallics (e.g. NiAl) are viewed as potential candidates for extending the performance envelope of advanced superalloys and other high-temperature alloys. For high temperature applications, materials should possess not only high strength and reasonable toughness but also

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Slip planes and asymmetric slip in fatigue of iron single crystals

Cited by 31 publications

References 15 publications

Cyclic deformation and fatigue behaviour of ?-iron mono-and polycrystals

Cyclic deformation and fatigue behaviour of ?-iron mono-and polycrystals

Dislocation junctions as indicators of elementary slip planes in body-centered cubic metals

Thermal Fatigue of NiAl Single Crystals

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