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HIGH-TEMPERATURE INTERNAL-FRICTION PEAK IN 99.999 wt % SINGLE-CRYSTAL
ALUMINIUM
C. Su, T. Kê
To cite this version:
C. Su, T. Kê. HIGH-TEMPERATURE INTERNAL-FRICTION PEAK IN 99.999 wt % SINGLE- CRYSTAL ALUMINIUM. Journal de Physique Colloques, 1985, 46 (C10), pp.C10-359-C10-362.
�10.1051/jphyscol:19851080�. �jpa-00225465�
JOURNAL DE PHYSIQUE
Colloque C10, suppl6ment au n012, Tome 46, decembre 1985 page C10-359
HIGH-TEMPERATURE INTERNAL-FRICTION PEAK IN 99.999 wt % SINGLE- CRYSTAL ALUMINIUM
C.M. SU AND T.S.
KS
Institute of Solid State Physics, Academia Sinica, Hefei, China
Abstract
-
An internal-friction peak situated at 365°C (f = 1 Hz)recently observed by K$ et al. in 99.991 and 99.999 wt % aluminium single crystals prepared by the dynamic-annealing me- thod and was consideredasoriginatin from the climbing of dis- persive dislocations in aluminium./l$ In this report, the con- dition for the appearance and disappearance as well as the pecu- larities of this 365'C peak were studied systematically with 99.999 wt '$ aluminium single crystals subjected to various me- chanical and thermal treatments.I. Preparation of the Specimens
-
!The 99.999 % aluminium was produced in China containing a very small amount of Mg and Si, and traces of Cu, Fe, Mn and Sn, and its nominal purity is 99.9993 %. Heavily cold- worked (swaging and drawing) 99.999 '$ aluminium wires (about 1 mm dia- meter) were annealed at 380°C for 2 h. They were deformed about 3 % by stretching at room temperature and put inside a tube furnace having a temperature gradient about 200'C/cm along the tube. The specimen was displaced in the furnace with a uniform speed of 2.5 cm/h. When the hottest part of the specimen inside the furnace was kept at a tempera- ture about 560°C, single-crystal wire was obtained without containing any grain boundaries. The variation of the angle between the crystal plane and the specimen axis is smaller: than 1' along the whole length ofthe specimen ( $ 2 cm). When the hottest part of the specimen was lowered to 460°C, "single-crystal" wire containing several bamboo grains of several cm long can also be obtained, and there are s2me small-angle grain boundaries with a deflection angle of about 5.
11. Experimental Results
-
Internal friction was measured with a low frequency inverted torsion pendulum. The length of the wire specimen was 12 cm. The maximum strain amplitude on the surface of the specimen was lower than All the internal friction curves (versus tempera- ture) were obtained by measurements with descending temperatures.11. 1. Effect of the method of growth and the procedure of heat treatment on the appearance of the 365°C peak.
1. Crystal grown by low-temperature dynamic annealing ( 4 6 0 ~ ~ ) A specimen containing 4--5 bamboo boundaries in a length of 12 cm was annealed at 430°C for 2 h. The internal friction measured in des- cending temperatures is shown by curve 1 of Fig. 1 . A low internal- friction peak appeared around 300°C which has been shown to be the maerocrystalline internal-friction peak./2/ The specimen was then an- nealed in situ of the torsion apparatus at 6 0 0 " ~ for 2 h. Then the temperature was lowered to 430°C and kept there for 2 h. Internal friction measurements were taken with descending temperatures and the internal friction curve obtained is shown by curve 2 of Fig. 1 . It can Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:19851080
C10-360 JOURNAL DE PHYSIQUE
be seen that the 600°C annealing
365°C peak. led to the appearance of a pronounced
Pig. 1
.
Internal friction ( Q - I ) Fig. 2. Internal friction ( Q - { ) curves of A1 single crystal curves of A1 single crystal grown grown by low-tem erature dynamig by static annealing (450°C).annealing (4606C7. Curve 1. 430 Curve 1, 4508C anneal for 2 h.
C anneal for 2 h. Curve 2. 600°C Curve 2, 3, 4. 480, 513, and anneal for 2 h. Strain amplitude 550°C anneal for 2.5 h.
A, = 7 x 1,0-~.
Figure 2 shows the internal friction curves of a crystal grown by low-temperature static annealing, which contains about 10 bamboo boun- daries after an annealing at various temperatures. It is seen thzt the 360°C peak appears only after an annealing at 550°C.
2. Crystal grown by high-temperature dynamic annealing (560%) For such a crystal, the 365'C peak appeared after an annealing at 4308C as shown by curve 1 of Fig. 3. This happens because the crystal has been treated at a temperature higher than 550°C during its growth.
Previous experiments / I / showed that the 3656C peak did not appear in a single crystal grown by zone-melting. This means tha-t the condi- tion for the appearance of the 365OC peak is that the specimen must be stretched (about 3 '$ or so) and then subjected to static or dynamic
TC'CI 400 350 300 z50
Fig. 3. Internal friction curve
i of A1 single crystal grown by i high-temperature dynamic anneal-
ing (560eC). Curve 1
.
430C an->
- neal for 2 h. Curve 2. Creepdeformation of 5 % (height of the 365'C peak drops from A to B). Curve 3. 620°C anneal for
1.5 h, showing the disappearance of the 365'C peak and the ap- pearance of the macrocrystal- line peak.
I 4 16 1 8 2 0
l000,T I N - ' ,
annealing so that the specimen was heated up to a temperature above 550°C. In the case of growth by zone-melting,the growth process was proceeded by localized transformation between liquid and solid states so.that the defect state in the single crystal grown should be quite different from those in the crystal which had not been subjected to local melting.
11. 2. Effect of tensile deformation on the height of the 365°C peak
In curve 2 of Fig. 3, the internal friction was measured from 430°C with descending temperatures down to the peak temperature (765°C) and then a tensile stress of 2.9 X
lo7
dyne/cm2 was applied to the speci- men in situ of the torsion apparatus for 150 s to reach an elongation of 5 %. It is seen that the internal friction at 365°C dropped fromA
to B after this creep treatment. Then the temperature was raised to 620°C and kept there for 1.5 h, and the internal friction measured with descending temperatures is shown by curve 3. It is seen that the
365*C peak completely disappeared and the "macrocrystalline peak" re- appeared. Laue analysis showed that the specimen was polygonized but there was no trace of fine grains formed by recrystallization.
Tensile deformation at room temperature has the same effect as creep deformation in suppressing the height of the 365OC peak. For very small deformation at room temperature or by creep, the 365'C peak can be partially recovered by a subsequent annealing at 600eC.
11. 3. Activation energy associated with the 365°C peak The activation energy was de- TI.Ci
termined by the method of change 40C 350 300 230 Z O O 130 of frequency. Cautions were taken
for avoiding the specimen to be subjected to deformation during the change of frequency. The av- erage value of several measure- ments on different specimens is H = 1.84 $ 0.1 eVand 3. = T.4X
1014 Hz. Determination of the acti- vation energy by using a force vibration pendulum in which the
Q'I -f curves were measured at various temperatures ( T ) gave si- milar results (H = 1.81 e ~ ) as those determined by measuring the
Q - f -T curves at various fre-
quencies (f). Curves 1--4 of
Fig. 4 show the internal fric- 1 0 0 0 / 7 t K ')
tion curves measured with 1 , Fig. 4. Determination of the acti- 0.464, 0.215, 0.100 Hz in the vation energy associated with the temperature range of 430 to 365°C peak by force vibration tor-
T ~ O O C
.
sion pendulum. The variation ofQ - f with frequency was determined
at various temperatures. Curves f--4: with frequencies 1 , 0.464, 0.215 and 0.100 Hz respectively.
11. 4. Amplitude dependence of the 365OC peak
In Fig. 5 is shown the amplitude effect of the internal friction curves of a crystal grown by low-temperature dynamic annealing with subsequent annealing at 4308C and at 600°C for 2 h. Curves 1 and < k 450°C anneal, with strain amplitude (AE) : 9.1 X 10
-'
and 2 . 5 X 10.
Curves 3,
4,
5. 600°C anneal, with A& : 9.1 X lo-', 6.5 X and 4.5 X It is shown that, there is no amplitude effect for the macro-crystalline peak as shown by curves 1 and 2. Whereas anomalous amplitude effect appeared for the 365°C peak as shown by curves 3, 4, 5.JOURNAL DE PHYSIQUE
Pig. 5. The amplitude dependen- ce of the macro-crystalline peak and the 36!jBC peak. Curves
T , 2: 430°C anneal for 2 h, for
the macro-crystalline eak with
B
A t = 9.1 and 2.5, X 10-
.
Curves7,
4, 5: 600°C anneal for 2 h, for the 365'C peak, with A , =9.1, 6.5, and 4.5 .r( 10'~.
Fig. 6. The anomalous amplitude effect of the 36T°C peak. Curve A, B, C corresponds respectively to the temperature marked on c u n e 7 of Pig. 5.
In Fig. 6 are shown the Q - I -AE curveS at the three temperatures marked A , B and C on curve 7 of Fig. 5. It is seen that anomalous amplitude effect appears most pronouncedly near the peak temperature of the 365°C peak.
111. Discussions
-
Electron microscopic observations showed that under the conditions when only the 365'C peak appears, the dislocations in the specimen are arranged in an irregular spatial network in a disper- sive and homogeneous mode./3/ This is quite different from the highly inhomogeneous dislocation configuration in cell structures or polygo- nization boundaries.In consideration of the magnitude of the activation energy and the attempted frequency associated with the 365°C peak as determined in the present experiments, this 365OC eak is considered as originating
from the formation and the movement !climbing) of the jogs on the dis- locations constituting the spatial network, and the anomalously ampli- tude-dependent effectis.explained as due to the piling up of the jogs and the subsequent release because of the shift or the broken down of nodes of the dislocation network.
References
1 T. S. I($, P. Cui, and C. M. Su, phys. stat. sol. (a) s t 5 7 (1984).
12: T. S. K B , 6 . D. Zhang, P. Cui, Q. Huang, and B. S. Zhang, phys.
stat. sol. (a)
84,
465 (1984).T. S . Kg, P. Cui, S, C. Yan, and Q. Huang, phys. stat. sol. (a) 86, 964 (1984).
/7/
T.
S. KG, Proc. Yamada Conference IX on Dislocations in Solids, T'ok~o/~a an Au st 1988.T/4/ J. ahi,
