Original scientific paper
Dependence of microstructure of Al-44 at% and Al-48 at% zn alloys on temperature
Željko Skoko
; Physics Department, Faculty of Science, University of Zagreb, Bijeniˇcka cesta 32, HR-10002 Zagreb, POBox 331, Croatia
Stanko Popović
; Physics Department, Faculty of Science, University of Zagreb, Bijeniˇcka cesta 32, HR-10002 Zagreb, POBox 331, Croatia
Abstract
The temperature dependence of microstructure of the title alloys was studied in situ by XRD. Each alloy had been subjected to two different thermal treatments: (i) rapid quenching from the solid-solution temperature, TSS, in water at room temperature (RT) and ageing at RT (samples WQ) and (ii) cooling slowly from TSS to RT and ageing at RT (samples SC). As the samples SC were closer to the equilibrium state than the samples WQ, the microstructure of the two sets of samples dependeded on temperature in a different way. The solid solution, αSS, was formed at about 720 K for the samples SC, and at about 880 K for the samples WQ. During the slow cooling to RT the samples SC and WQ behaved in a similar way. Instead of the phase transitions expected according to the phase diagram, the following sequence of transitions was observed for both alloys: α(M/β)+β(Zn) – α0 +β(Zn)+α(M/α0 ,β) – αSS. A similar thermal behaviour was also found for the Zn-rich alloys, Al-54 at% Zn and Al-62 at% Zn.
Keywords
Al-Zn alloys; solid solution; phase transition; phase diagram; X-ray powder diffraction
Hrčak ID:
301564
URI
Publication date:
1.10.2001.
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