Compositional softening in Mg-Al spinel

Donlon, W. T.; Heuer, A. H.; Mitchell, T. E.

doi:10.1080/01418619808241926

Cited by 16 publications

(24 citation statements)

References 26 publications

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“…This was first realized for prism and basal slip in sapphire, 53,57 and then it was recognized that this relationship is equally valid in spinel, 24,25 as shown in Fig. 11.…”

Section: Critical Resolved Shear Stressmentioning

confidence: 93%

“…The straight lines for a given value of n are parallel and data from various authors agree remarkably well. 1,3,15,24 The data in Fig. 11 are for {111} slip, but equivalent straight lines are obtained for {110} slip with a slightly lower slope and lower absolute values, except at the highest temperatures, where the CRSS is the same for both systems.…”

Section: Critical Resolved Shear Stressmentioning

confidence: 93%

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Dislocations and Mechanical Properties of MgO‐Al2O3 Spinel Single Crystals

Mitchell

1999

Journal of the American Ceramic Society

103

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MgOؒnAl 2 O 3 spinel single crystals can be deformed plastically at high temperatures, displaying a range of interesting features. Stress-strain curves often exhibit strong work hardening followed by prominent work softening due to glide and climb processes. The critical resolved shear stress (CRSS) at a given temperature decreases dramatically, by almost 2 orders of magnitude, with increasing deviation from stoichiometry, i.e., as n increases from 1 to 3.5. The CRSS is proportional to exp(−T/T 0 ) and to [V c ] −2 , where T is the temperature in kelvin, T 0 a characteristic tempera- ture, and [V c ] the concentration of charge-compensating cation vacancies. The Burgers vector is 1/2〈110〉, and slip can occur on {111} and {110} planes. Slip on {111} planes is believed to occur between the Kagomé cation layer and the adjacent anion layer. Slip on {110} planes is slightly easier(and has a higher T 0 ), because the planes are more widely separated. The temperature dependence of the CRSS can be explained in terms of the Peierls stress for partial dislocations, either in terms of a steep and high Peierls potential or in terms of temperature and stress-dependent kink diffusion. The dependence of CRSS on [V c ] −2 can be explained in terms of kink nucleation at cation vacancies.

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“…This was first realized for prism and basal slip in sapphire, 53,57 and then it was recognized that this relationship is equally valid in spinel, 24,25 as shown in Fig. 11.…”

Section: Critical Resolved Shear Stressmentioning

confidence: 93%

Section: Critical Resolved Shear Stressmentioning

confidence: 93%

Dislocations and Mechanical Properties of MgO‐Al2O3 Spinel Single Crystals

Mitchell

1999

Journal of the American Ceramic Society

103

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“…The value of Q is much higher for stoichiometric spinel (4.7 eV), which has an even stronger temperature dependence. Q has the same value for {111} and {110} slip because the CRSS is reported to be the same for stoichiometric spinel [26]. However, in nonstoichiometric spinel ( Figure 9.5), the CRSS values are lower for {110} slip and have a lower temperature dependence (lower Q).…”

Section: Sapphire and Stoichiometric Spinelmentioning

confidence: 86%

“…In MgOÁnAl 2 O 3 (n > 1), the CRSS decreases dramatically with increasing deviation from stoichiometry; that is, with increasing n. In fact, the CRSS was found [26] to be proportional to [V c ] À2 , where [V c ] is the concentration of charge-compensating cation vacancies which is related to n by…”

Section: Modification Of the Model For Kink Pair Nucleation On Point mentioning

confidence: 99%

Dislocations in Ceramics

Mitchell¹

2010

Ceramics Science and Technology

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“…The strength of the spinel phase is known to be highly sensitive to its stoichiometry. 62 The composition of spinel particles deviates from stoichiometry due to the dissolution of magnesium into the ZrO 2 matrix and due to the solution of zirconium [ Fig. 2(e)].…”

Section: Role Of Spinel Particle Dispersion For Attaining Hsrs In mentioning

confidence: 99%

Microstructural examination in high-strain-rate superplastically deformed tetragonal ZrO₂ dispersed with 30 vol% MgAl₂O₄ spinel

et al. 2007

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The role of MgAl 2 O 4 spinel particle dispersion for attaining high-strain-rate superplasticity (HSRS) was examined in tetragonal ZrO 2 . Microstructural examination shows that the dispersed spinel particles provide the following positive factors to ZrO 2 simultaneously: (i) stable fine grain size by retarding grain growth due to pinning effect; and (ii) enhanced accommodation due to accelerated lattice diffusivity caused by the dissolution of aluminum and magnesium into ZrO 2 from the spinel particles, and accelerated relaxation of stress concentrations exerted by grain boundary sliding through dislocation motion. These positive factors make it possible to attain HSRS in ZrO 2 .

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Compositional softening in Mg-Al spinel

Cited by 16 publications

References 26 publications

Dislocations and Mechanical Properties of MgO‐Al2O3 Spinel Single Crystals

Dislocations and Mechanical Properties of MgO‐Al2O3 Spinel Single Crystals

Dislocations in Ceramics

Microstructural examination in high-strain-rate superplastically deformed tetragonal ZrO₂ dispersed with 30 vol% MgAl₂O₄ spinel

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Compositional softening in Mg-Al spinel

Cited by 16 publications

References 26 publications

Dislocations and Mechanical Properties of MgO‐Al2O3 Spinel Single Crystals

Dislocations and Mechanical Properties of MgO‐Al2O3 Spinel Single Crystals

Dislocations in Ceramics

Microstructural examination in high-strain-rate superplastically deformed tetragonal ZrO2 dispersed with 30 vol% MgAl2O4 spinel

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Microstructural examination in high-strain-rate superplastically deformed tetragonal ZrO₂ dispersed with 30 vol% MgAl₂O₄ spinel