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 Structural and morphological investigations of the processes occurring in Al-9 wt% Si silumin during isothermal ageing at high temperatures were performed using hardness measurements and electron microscopic observations. It was established that the alloy achieved maximum hardness after being aged for 2.7×103 sec at a temperature of about 463 K. During this time, formation of clusters of supersaturating atoms, probably of spherical symmetry, was observed, and which, as the ageing time lengthened, assumed the form of needles (GP zones). It is suggested that GP zones contain “foreign” atoms (impurities, e.g. Fe, Mn, Na) which may tend to increase the stability of these zones. During continued ageing, in the period between 1.1×104 and 2.2×104 sec, excess silicon precipitates appeared. These precipitates increased in size progressively as the ageing time was increased, whereas the GP zones, after reaching a certain magnitude, remained unchanged. The change GP zones →β′-phase rod-like precipitates occurs after ageing for approximately 8.6×104 sec. Differences between the course of ageing in Al-9 wt% Si silumin and in (after supersaturation) single-phase alloys from a pseudobinary Al-Mg2Si system, are discussed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00611455
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