FIZIKA A 8 (1999) 3 , 173-182

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TEMPERATURE DEPENDENCE OF MICROSTRUCTURE IN Zn-Al ALLOYS

STANKO POPOVIĆa, BISERKA GRŽETAb, BRANKO HANŽEKc
and SNJEŽANA HAJSTERa

aPhysics Department, Faculty of Science, University of Zagreb, Bijenička cesta 32, 10001 Zagreb, Croatia

b``R. Bošković" Institute, Bijenička cesta 54, 10001 Zagreb, P.O.Box 1016, Croatia

cMinistry of Education, Trg burze 6, 10000 Zagreb, Croatia

Dedicated to Professor Boran Leontić on the occasion of his 70th birthday

Received 10 December 1999; Accepted 28 February 2000

The temperature dependence of microstructure in Zn-Al alloys, transferred to the equilibrium state by quenching from the solid solution temperature, TSS, to room temperature (RT) and prolonged ageing at RT, was studied in situ by X-ray powder diffraction. Instead of the phase transitions expected according to the phase diagram, namely  a(M/b) + a' + a(M/a') ® aSS  for the alloy with 54 at% Zn and a(M/b) + a'+ aSS  for the alloy with 62 at% Zn, the following sequence was observed for both alloys: a(M/b) + a' + b+ a(M/a', b) ® a'+ aSS. In the cooling run, a temperature hysteresis in reversal phase transitions was observed. During a repeated heating, the microstructure depended on the previous thermal treatment of the alloys.

PACS numbers: 61.50.-f, 64.70, 64.75.-p, 64.75.+g, 65.70.+y
UDC 548.73
Keywords: Zn-Al alloys, solid solution, phase transition, phase diagram, X-ray powder diffraction
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