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FIZIKA A 15 (2006) 1 , 61-72
 
TEMPERATURE DEPENDENCE OF MICROSTRUCTURE OF (1-x)Al-xZn
ALLOYS,
x = 0.44, 0.48, 0.54 AND 0.62
ŽELJKO SKOKO and STANKO POPOVIĆ
Physics Department, Faculty of Science, University of Zagreb,
Bijenička cesta 32, HR-10002 Zagreb, P.O. Box 331, Croatia
E-mail address: zskoko@phy.hr,
spopovic@phy.hr
Received 21 January 2005; revised manuscript received 13 October 2005
Accepted 17 October 2005 Online 10 November 2006
The change of microstructure with temperature of the title alloys
has been studied in situ by X-ray powder diffraction.
It has been found that the temperature dependence of microstructure
of the alloys, rapidly quenched from the solid-solution
temperature, Tss, to room temperature, RT, is quite different from that of the alloys slowly cooled
from Tss to RT. The area between two curves showing that
dependence for the given phase during the first heating from RT to Tss and first cooling from Tss to RT is much
smaller for the slowly-cooled alloys than for the rapidly quenched
alloys. That area slightly increases with the increase of
the Zn content in the alloys.
The temperature dependence of microstructure of the alloys
during the second heating from RT to Tss and second cooling
from Tss to RT differs little from that during the first
cooling from Tss to RT.
The ideal equilibrium state cannot be reached either by slow cooling
of the alloys from Tss to RT, or by a prolonged ageing at RT
of the rapidly quenched alloys. The observed sequence of phase
transitions in alloys during heating from RT to Tss
is different from that which could be expected according to the
phase diagram of the system Al-Zn accepted in the literature.
During cooling from Tss to RT, a temperature hysteresis is
observed in reversal phase transitions.
PACS numbers: 61.50.-f, 64.70, 64.75.-p, 64.75.+g, 65.70.+y
UDC 548.73
Keywords:
Al-Zn alloys, microstructure, phase transition, solid solution,
X-ray powder diffraction
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