ISSN:
1662-9752
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
The aging of Al-Zn alloys has been vastly studied for decades. In the previous paper, 0htaet al. studied carefully the hardness of the alloy during aging and revealed the existence of softerregions near the surface and the grain boundary than the interior of the specimen even after agingfor a long time. Electrical resistivity measurement and X-ray small angle scattering experimenttogether with hardness test suggested that in these regions vacancy decay to the surface and grainboundaries was severe, thus the growth of GP zones were suppressed and therefore age hardeningwas retarded. Also, it is well-known that an addition of a small amount of Ag raised solvustemperature of GP zones. In this paper, soft surface layer formed in an Al-12mass%Zn alloy isstudied by adding small amount of Ag by means of hardness test and resistometry. Addition of Agmore than 0.1% decreases the thickness of soft surface layer as well as accelerates age hardeningrate and suppresses the formation of soft region near the grain boundaries. Higher quenchingtemperature also reduces the thickness of soft surface layer. Together with the behavior of agingcurves of the specimen with various thicknesses, the origin of the soft surface layer is confirmed tobe the effective role of surface as sinks for vacancies
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/13/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.519-521.1883.pdf
