Microhardness investigations on manganese aluminate spinels

Dekker, E. H. L. J.; Rieck, G. D.

doi:10.1007/bf00541755

Cited by 36 publications

(6 citation statements)

References 12 publications

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“…Moreover, some work has been performed by indentation testing. 12,26,27 In comparison with the MgO-Al 2 O 3 system, relatively little work has been done on other spinels, with the exception of magnetite (Fe 3 O 4 ), 28 manganese zinc ferrite (Mn 0.7 Zn 0.2 Fe 2.1 O 4 ), 29 manganese aluminum spinel (Mn 1.8 Al 1.2 O 4 ), 30 nickel ferrite (Ni 0.7 Fe 2.3 O 4 ), [31][32][33] and chromite (FeCr 2 O 4 ). 34 Perhaps the most unusual mechanical behavior exhibited by MgOиnAl 2 O 3 spinel is compositional softening, whereby the critical resolved yield stress decreases by almost 2 orders of magnitude when the stoichiometry is changed from n ‫ס‬ 1 (stoichiometric) to n ‫ס‬ 3.5.…”

Section: Introductionmentioning

confidence: 99%

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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Section: Introductionmentioning

confidence: 99%

Dislocations and Mechanical Properties of MgO‐Al2O3 Spinel Single Crystals

Mitchell

1999

Journal of the American Ceramic Society

103

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“…It also shows that several cracks or median vents grow simultaneously from the concentration points, the sharp indentation edges. No preferred directions of venting were observed as in the case of anisotropic materials where the vents tend to have a preferred orientation (Dekker and Rieck 1974). Even for low loads, the deformation was too severe and near the indentation mark, the displaced matter I, igure I.…”

Section: Microhardness Testinmentioning

confidence: 96%

Measurements of the microhardness and compression testing of ferroelectric lead nitrate phosphate single crystals

Desai

Ramana

1987

Bull. Mater. Sci.

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“…3 Data reported in Smedskjaer et al (2008). 4 Data reported in Yuan et al (2017) 5 Data reported in Dekker and Rieck (1974). The reported data are averaged from the applied load at [110] and [100].…”

Section: Code Availabilitymentioning

confidence: 99%

The relaxation of residual inclusion pressure and implications to Raman-thermobarometry

Zhong

Moulas

Tajčmanová

2019

Preprint

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Abstract. Residual pressure can be preserved in mineral inclusions, e.g. quartz-in-garnet, after exhumation due to differential expansion between inclusion and host crystals. Raman spectroscopy has been applied to infer the residual pressure and provides information on the entrapment temperature and pressure conditions. However, the amount of residual pressure relaxation cannot be directly measured. An underestimation of pressure relaxation may lead to significant errors between calculated and actual entrapment pressure. This study focuses on three mechanisms responsible for the residual-pressure relaxation: 1) viscous creep; 2) plastic yield; 3) proximity of inclusion to thin-section surface. Criteria are provided to quantify how much of the expected residual pressure is relaxed due to these three mechanisms. An analytical solution is introduced to demonstrate the effect of inclusion depth on the residual pressure field when the inclusion is close to thin-section surface. It is shown that for quartz-in-garnet system, the distance between thin-section surface and inclusion centre needs to be at least two times the inclusion radius to avoid pressure relaxation. In terms of viscous creep, representative case studies on quartz-in-garnet system show that viscous relaxation may occur from temperatures as low as 600∼700 °C depending on the particular P-T path and various garnet compositions. For quartz entrapped along the prograde P-T path and subject to viscous resetting at peak T above 600∼700 °C, its residual pressure after exhumation may be higher than predicted from its true entrapment conditions. Moreover, such a viscous resetting effect may introduce apparent overstepping of garnet nucleation that is not related to reaction affinity.

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Microhardness investigations on manganese aluminate spinels

Cited by 36 publications

References 12 publications

Dislocations and Mechanical Properties of MgO‐Al2O3 Spinel Single Crystals

Dislocations and Mechanical Properties of MgO‐Al2O3 Spinel Single Crystals

Measurements of the microhardness and compression testing of ferroelectric lead nitrate phosphate single crystals

The relaxation of residual inclusion pressure and implications to Raman-thermobarometry

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