Non compact glide in face centered cubic metals

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Non compact glide in face centered cubic metals

M. Carrard

To cite this version:

M. Carrard. Non compact glide in face centered cubic metals. Revue de Physique Appliquée, Société

française de physique / EDP, 1988, 23 (4), pp.678-678. �10.1051/rphysap:01988002304067800�. �jpa-

00245827�

678

NON COMPACT GLIDE IN FACE CENTERED CUBIC METALS M. Carrard

EPF Lausanne, ^{Institut de Génie} Atomique

1015 - Lausanne (Switzerland)

Revue Phys. Appl. ²³ (1988) ^{678 AVRIL 1988,}

The present knowledge ^{and ideas on non} compact glide in pure f.c.c. metals ^are reviewed, ^with special ^{reference to Aluminium} single crystals.

These glide systems, ^{which were} considered in past

as abnormal or exceptional, ^{have in} fact their own

Burgers vectors and well ^defined slip planes ^and

seem to obey the Schmid Law. Moreover, they ^become

easy ^at high temperatures, ^where they ^can replace completely ^{the normal} compact slip systems (see,

for example, [1-9]).

Several non compact slip planes ^{have been ob-} served, ^{such as} (001), (110), (112), ^{(113) in} single crystals ^and polycrystals ^{for various}

f.c.c. metals, ^{such as} Aluminium, Copper, Silver, Gold and Nickel. Although ^their study ^{has been} performed mainly by slip ^line observations, ^non compact glide activation affect also the deforma- tion ^curve shape, ^the dislocation substructure and the slip ^mode during ^{in situ} experiments.

The stress-strain curves present ^a sharp ^de-

crease in hardening ^when non-compact glide ^{is acti-} vated (see figure 1). The stress corresponding ^to

this decrease can be directly ^related to the cri- tical resolved shear stress for the corresponding non-compact glide. Figures ^{1 and 2 show that this}

stress decreases rapidly ^with temperature. ^Non compact glide ^{are therefore} strongly thermally

activated with an apparent activation enthalpy

close to 1.7 eV for (001) glide ^{and 1.4 eV for} (110) glide.

Among the different models, ^the nucleation and propagation ^{of kink} pairs ^{on screw} dislocations

seems to be more appropriate to account for all these observations. The comparison ^{of the differ-}

ent apparent activation enthalpies measured in Aluminium show that non compact glide ^{can be a}

Figure 1. Stress-strain curves in [112] ^{Al single}

crystals ^for (001) glide [2]. ^{The arrows} correspond

to the critical stress for glide ^{on the} (001) plane. ^At 299 ° C1, only (111) glide ^{is activated.}

(y

12.10 sec ).

creep ^rate controlling mechanism at the beginning

of the high temperature ^domain. Besides, ^{it can} also explain ^the abnormally high ^{values of} apparent activation enthalpy ^found systematically

in high temperature creep ^of Copper.

This review shows that non compact glide ^takes

a prominent part ^{in the} deformation processes at

high temperatures. ^This importance ^{was unsus-} pected up to ^now and only two detailed studies exist. Consequently ^it appears urgent ^{to undertake} similar investigations ^{with different} single crystal orientations and various f.c.c. metals.

Figure 2. Critical resolved shear stress for (001) glide ^versus temperature ^{for three different}

strain rates ^{(1 : 03B3} = 12.10-5 sec-1, ^{2 : 03B3}

12.10-4 sec- 1, 3 : 03B3 = 12.10-3 sec-’). ^{The curves}

correspond ^{to the kink} pair ^model [2].

References :

[1] Carrard ^{M. and Martin} J.L., ^ICSMA 7, Montreal, 1985, p. 665.

[2] ^{Carrard M., Doctorate} Thesis, Lausanne, ^1985.

[3] Bonneville J., ^Caillard D., Carrard M., ^Martin J.L., ^this conference.

[4] ^{Carrard M. and Martin J.L., Phil. Mag.,}

accepted ^for publication, ^1987.

[5] ^{Le Hazif R., Dorizzi} P. and Poirier J.P., ^Acta Met., ²¹ (1973) 903.

[6] ^{Le Hazif R. and Poirier J.P., Acta Met., 23}

(1975) ^865.

[7] Lacombe P. and Beaujard L., ^{J. Inst.} Met., ⁷⁴ (1947) ^1.

[8] ^Johnson R.D., Young ^{A.P. and} Schwope A.D.,

Proc. of a Symposium ^{on the} Creep and Fracture of Metals at high temperatures, London,1956,

p. 25.

[9] ^Cahn R.W., ^{J. Inst.} Metals, ⁷⁹ (1951) 129.

Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/rphysap:01988002304067800