Temperature dependence of microstructure of Al-Ag- Zn alloys (CROSBI ID 542528)
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Podaci o odgovornosti
Popović, Stanko ; Skoko, Željko ; Štefanić, Goran
engleski
Temperature dependence of microstructure of Al-Ag- Zn alloys
Al-rich Al-Ag-Zn alloys, quenched to RT from a temperature, Tt, higher than the solid-solution temperature, Tss, contained GP zones, as proved by XRD and TEM. GP zones grew during ageing, remaining fcc and coherent with the Al-rich α - phase (fcc). In parallel, metastable precipitates, ε ´ (hcp), were formed by discontinuous nucleation and by a direct transition from GP zones. The unit-cell parameters of ε ´ and of the equilibrium phase, ε (hcp), formed in the alloys slowly cooled from Tt to RT, depended on the solute content. The quenched and prolongedly aged alloys, being two- phase systems, α + ε ´, were studied in situ at high temperature. The following was observed: an initial lattice strain annealing, an anisotropy of thermal expansion of ε ´, a gradual dissolution of ε ´ in the α -phase above 500 K, the formation of solid solution. Tss depended on the alloy composition. On cooling, a temperature hysteresis was noticed in reversal changes. The dependence of unit-cell parameters of ε ´ on temperature during cooling was different from that during heating. After the heating and cooling cycle, unit-cell parameters of the precipitates were close to those of the equilibrium phase, ε .
XRD; alloys; phase transitions; Al-Zn-Ag
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Podaci o prilogu
114-115.
2008.
objavljeno
Podaci o matičnoj publikaciji
11th European Powder Diffraction Conference Abstracts
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Podaci o skupu
11th European Powder Diffraction Conference
poster
19.09.2008-22.09.2008
Varšava, Poljska