ISSN:
1573-4803
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract The influence of Mg concentrations on the dissolution of Guinier-Preston (GP) zones formed at room temperature (RT) and on the formation of more stable phases has been investigated during continuous heating of Al-4.5 at % Zn-xMg alloys. The Mg content was varied from 0.05 to 3 at %. After different aging periods at RT, calorimetric investigations were carried out at heating rates of 40 and 80° C min−1. In the case of alloys with a lower Mg content (x ⩽ 0.5 at %) only the dissolution of GP zones could be observed during the heating, whereas in the case of alloys with a higher Mg content the formation of theη′-phase started before the total dissolution of GP zones and at higher temperatures the formation of theη-phase also took place. These phases were identified by transmission electron microscopy. The heat-of-solution of GP zones shows saturation as a function of RT aging time. The time needed for the saturation increased monotonously with increasing Mg content. The reversion of zones was followed byin situ X-ray small angle scattering measurements. The change of the total scattered intensity was measured during continuous heating at a rate of 40° C min−1. These investigations have confirmed the results of the calorimetric measurements which indicate that the total dissolution of zones takes place only in the case of the alloys with a Mg content lower than 0.5 at %. In the case of alloys with a Zn concentration of 4.5 at % studied here, 1 at % Mg is sufficient to initiate the formation of more stable phases during the reversion of zones.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02402832
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