Microstructural changes in the AlCaZn superplastic alloy studied by positron lifetime spectroscopy

The effect of microstructural changes by thermal treatments of superplastic Al--5Ca--5Zn alloy at 798K on the positron annihilation characteristics was studied. Based on linear intercept method, the measured growth of intermetallic phase of CaZnAl3 particles slowed down with increasing annealing tim...

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Bibliographic Details
Published in:Scripta metallurgica et materialia 1990-11, Vol.24 (11), p.2225-2229
Main Authors: Romero, R., Silvetti, S.P., Somoza, A.
Format: Article
Language:English
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Summary:The effect of microstructural changes by thermal treatments of superplastic Al--5Ca--5Zn alloy at 798K on the positron annihilation characteristics was studied. Based on linear intercept method, the measured growth of intermetallic phase of CaZnAl3 particles slowed down with increasing annealing time and temperature with the appearance of spheroidal particles of a second phase after 1 h at 823K. The specific surface change of both grain boundaries and interphases decreases on annealing by approx 43% between 1-35 h which is comparable with the variation of intensity in the two-term analysis of the spectra. The variation in positron lifetime parameters as a function of isothermal annealing time indicates a decrease in the trapping centers of second-phase particles and grain boundaries with increasing annealing time. Graphs. 12 ref.--B.C.(UK/US).
ISSN:0956-716X
DOI:10.1016/0956-716X(90)90515-I