Compressive Creep of CoO Single Crystals

Krishnamachari, V.; Jones, J. T.

doi:10.1111/j.1151-2916.1974.tb11410.x

Cited by 20 publications

(7 citation statements)

References 8 publications

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“…T > 0.6 TM) [3][4][5][6][7][8][9]. These two oxides appear to be similar with metal deficient nonstoichiometry, NaCI type crystal structure (lattice parameter 0.418 nm for NiO and 0.426 nm for CoO) and antiferromagnetic ordering at low temperature (TN = 525 K for NiO and 290 K for CoO).…”

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confidence: 87%

Plastic deformation of CoO single crystals

Castaing

Spendel

Philibert

et al. 1980

Rev. Phys. Appl. (Paris)

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confidence: 87%

Plastic deformation of CoO single crystals

Castaing

Spendel

Philibert

et al. 1980

Rev. Phys. Appl. (Paris)

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“…Dislocation multiplication and glide are regarded as hardening mechanisms and dislocation annihilation and climb as recovery mechanism. Krishnamachari and Jones [8] have suggested that dislocation climb mechanism is operative during high temperature creep of CoO single crystals. They obtained a fifth power stress exponent for the steady state creep rate, and the activation energy for creep was 66.1 _+ 5.4kcalmo1-1 , which they attributed to the oxygen controlled pipe diffusion.…”

Section: Experimental Procedures and Resultsmentioning

confidence: 99%

“…of two competing processes: work hardening and recovery [12][13][14]. Clauer et al [9] and Krishnamachari and Jones [8] have observed the formation of subgrain walls during high temperature creep. At high temperatures dislocations can climb out of the slip plane by diffusional mass transport of atoms and form subgrain boundaries.…”

Section: Experimental Procedures and Resultsmentioning

confidence: 99%

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Creep recovery of CoO single crystals

Krishnamachari

1976

J Mater Sci

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The recovery of creep resistant substructure in CoO single crystals was studied at temperatures of 1000, 1050, and 1100 ~ C in air. Compressive creep specimens were crept under a stress of 13.8 MN m -2. to a strain early in the secondary stage of creep, then allowed to recover for varying periods of time under a reduced stress of 0.69 MN m -2 . Recovery was detected by increased amounts of creep strain which occurred upon reapplication of the 13.8 MN m -2 stress. An apparent activation energy of 71.7 -+ 10 kcal mol -a was obtained for the recovery process. Experimental evidence suggests that the primary recovery mechanism involves the climb of dislocations within subgrain boundaries.

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“…4 Co i ] 3À [23]. Figure 5 The results of the creep studies of CoO single crystals [24][25][26][27][28] and CoO polycrystals [14] are summarized in Table 1. A comparison of the activation energies for creep rate with oxygen self-diffusion obtained by Dubois et al [15,16] agrees only with a rather large uncertainty.…”

Section: Creep Of Coomentioning

confidence: 99%

High Temperature Creep of Metal Oxides

Schneider¹,

Rękas²

2018

Creep

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This chapter presents a comprehensive review of the creep technique used for the study of defect structure and diffusion in metal oxides, both single crystals and ceramics. At high temperatures, the creep rate is proportional to the diffusion coefficient of the slowest species in solid compounds, whatever deformation mechanisms are present (Nabarro viscous creep, recovery creep or pure climb creep). The creep rate dependence on deviation from stoichiometry can be determined from this diffusion. In the case of metal oxides, the departure from stoichiometry is controlled by the oxygen activity which usually is identified with oxygen partial pressure, p O 2 . The p O 2 dependence of the creep rate provides direct information about the nature of minority point defects. On the other hand, studies of the temperature dependency of the creep rate inform us about the activation energy of the diffusion coefficient.This review focuses primarily on the creep behavior of transition metal oxides such as Ni 1Ày O, Co 1Ày O, Fe 1Ày O exhibiting disorder in metal sublattice, as well as ZrO 2Àx with majority defects in oxygen sublattice. The advantage of these studies is determination of both defect structure and diffusion coefficients of minority defects namely in oxygen sublattice in iron-triad oxides and in zirconium ZrO 2 sublattice.

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Compressive Creep of CoO Single Crystals

Cited by 20 publications

References 8 publications

Plastic deformation of CoO single crystals

Plastic deformation of CoO single crystals

Creep recovery of CoO single crystals

High Temperature Creep of Metal Oxides

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