Overview no. 5

Gandhi, C.; Ashby, Michael F.

doi:10.1016/0001-6160(79)90042-7

Cited by 251 publications

(48 citation statements)

References 85 publications

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“…[lo] and Gandhi and Ashby [50] sitivity, of tensile strength of coarse-grained (3 to reveals that failure by intergranular cracking 4mm) columnar-grained ice observed by Carter commonly occurs above o/E = 5 x lo-' and is and Michel [47] and of fine-grained (0.7 mm) therefore similar to that in ice. At these low stress granular ice examined at high strain rates by levels (still too high for pure diffusional creep to Hawkes and Mellor [48] corroborates these values.…”

Section: Discussionmentioning

confidence: 98%

Intercrystalline cracking, grain-boundary sliding, and delayed elasticity at high temperatures

Sinha

1984

J Mater Sci

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/npsi/ctrl?lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?lang=fr Access and use of this website and the material on it are subject to the Terms and Conditions set forth at http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. Science, 19, pp. 359-76, 1984 Intercrystalline cracking, grain-boundary sliding, and delayed elasticity at high temperatures Sinha, N. K. Journal of Materials Journal of Materials Science is published monthly byChapman and Hall Ltd., 11 New Fetter Lane, London EC4P 4EE, from whom subscription details are available. 19 (1984) 359-376 Intercrystalline cracking, grain-boundary sliding, and delayed elasticity at high temperatures NIRMAL K. SINHA Division of Building Research, National Research Council of Canada, Ottawa, Canada JOURNAL OF MATERIALS SCIENCEThe hypothesis of an interrelation between grain-boundary sliding and delayed elasticity in polycrystalline materials at high homologous temperatures is used to investigate the conditions conducive to microcracking. It is known that a material may exhibit cracking activity on attaining a critical delayed-elastic strain corresponding to a critical grainboundary sliding displacement. Experimental data on ice at temperatures > 0.9 T, are used to verify this concept. The new criterion is then extended to develop simple, selfconsistent equations describing the interdependence of stress, strain, time, temperature, and grain size in predicting the onset of structural degradation due to microcracking and hence possible failure by fracture or rupture. The merit of the theory lies in its ability to forecast explicitly a large number of commonly observed high-temperature phenomena, including superplasticity, brittle-ductile transition, and the stress and temperature dependence of the apparent activation energy for fracture. One derivation makes it clear that cracking occurs when a critical stress depending only on temperature (and independent of grain size) is exceeded. The near constancy of fracture strain in the quasi brittle range can also be predicted

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Section: Discussionmentioning

confidence: 98%

Intercrystalline cracking, grain-boundary sliding, and delayed elasticity at high temperatures

Sinha

1984

J Mater Sci

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“…The strength of Mo at an elevated temperature is much higher than that of NiAl (E Mo ¼ 300 GPa, E NiAl ¼ 151 GPa, at 900 C). 1,24) These are enough to indicate that the creep process is accomplished mainly via the deformation in NiAl phase. The subgrain boundaries were also observed in NiAl phase from the Fig.…”

Section: Steady-state Creepmentioning

confidence: 96%

“…The elevated temperature strength of Mo is much higher than that of NiAl (E Mo ¼ 300 GPa, E NiAl ¼ 151 GPa, at 900 C). 1,24) Moreover, the Mo phase of only 12 volume percent is uncontinously distributed in the matrix. The size and morphology of the Mo phase in the grain cell remain unchanged after the sample crept.…”

Section: Creep Activation Energymentioning

confidence: 99%

Creep Characteristic of NiAl-9Mo Eutectic Alloy

et al. 2004

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The creep behavior of NiAl-9Mo eutectic alloy has been studied in an effort to understand the characteristic that the alloy exhibits of the low stress exponent of 4.75 and the high apparent activation energy of 410 kJ/mol during the steady-state creep of under the test conditions. The material exhibits threshold behavior with a threshold stress of 17.9 MPa. TEM observation reveals that the creep deformation is mainly governed by dislocation climb in NiAl matrix phase. Large recoverable strain is observed after unloading under the transient creep and increases with the increase of stress or temperature. It exhibits an activation energy 232 kJ/mol, suggesting the processes is controlled by the flow behavior of the matrix phase. The apparent creep activation energy under constant stress is a combination of the creep flow activation energy of the matrix and the activation energy for the damage process at the phase interface.

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“…Despite this simplified geometry, it is felt that the failure maps presented here are likely to be representative of the mechanisms governing the failure of these 17-4 PH sandwiched foam fans. As with any deformation [28] and fracture [29] maps, the positions of the regime boundaries on the maps depend both on the accuracy of the equations describing the failure loads as well as the quality of the data used in generating the maps. A rotating fan blade experiences several types of loading profiles during service ( fig.…”

Section: Loading Conditions On a Fan Bladementioning

confidence: 99%