Low-temperature creep in aluminium has been studied by means of change-in-stress experiments. The value of the flow parameter B (= ∆ ln έ/∆τ) was higher for creep following stress decrements than that for creep following increments, the difference being negligible at higher stresses. Among the various possible mechanisms considered, a model based on the formation of attractive junctions following a stress decrement, causing a change in the number of dislocation elements participating in the activation event, explains the effect satisfactorily.
Get full access to this article
View all access options for this article.
References
1.
CottrellA. H., “Dislocations and Plastic Flow in Crystals p. 206. 1953: Oxford(Clarendon Press).
2.
ThorntonP. R. and HirschP. B., Phil. Mag., 1958, 3, 738.
3.
ConradH., Acta Met., 1958, 6, 339.
4.
MitraS. K., OsborneP. W., and DornJ. E., Trans. Met. Soc. A.LM.E., 1961, 221, 1206.
5.
LyttonJ. L., ShepardL. A., and DornJ. E., ibid., 1958, 211, 220.
6.
RocherY. A., ShepardL. A., and DornJ. E., ibid., 1959, 215, 316.
7.
WyattO. H., Proc. Phys. Soc., 1953, 66, 459.
8.
SastryD. H., PrasadY. V. R. K., and VasuK. I., Acta Met., 1969, 17, 1453.
9.
SastryD. H., PrasadY. V. R. K., and VasuK. I., to be publishedin Current Sci. (India).
10.
ConradH., HaysL., SchoeckG., and WiedersichH., Acta Met., 1961, 9, 367.
11.
PrasadY. V. R. K., SastryD. H., and VasuK. I., J. Indian Inst. Sci., 1969, 51, 377.
12.
SeegerA., “Dislocations and Mechanical Properties of Crystals" (edited by J. C. Fisher et al.), p. 243. 1957: New York and London(John Wiley).
13.
MitraS. K. and DornJ. E., Trans. Met. Soc. A.L.M.E., 1963, 227, 1015.
14.
HirthJ. P. and LotheJ., “Theory of Dislocations ”, p. 540. 1968: New York and London(McGraw-Hill).
15.
PrasadY. V. R. K., SastryD. H., and VasuK. I., Current ScL (India), 1969, 38, 403.
16.
McLeanD., “Mechanical Properties of Metals ”, pp.33, 98. 1962; New York and London(John Wiley).
17.
SaadaG., Acta Met., 1960, 8, 200; “Electron Microscopy and Strength of Crystals” (edited byThomasG. and Wash-burnJ.), p. 651. 1963: New York and London(Interscience Publishers).
18.
ForemanA. J. E. and MakinM. J., Phil. Mag., 1966, 14, 911.
19.
KocksU., ibid., 1966, 13, 541.
20.
DornJ. E., “Dislocation Dynamics” (edited byRosenfieldA. R. et al.), p. 420. 1968: New York and London(McGraw-Hill).
