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 liquid film re-growth behaviour resulting from pulsed laser surface melting (LSM)has been investigated for typical 2xxx, and 7xxx aerospace alloys, both on parent plate and frictionstir welded (FSW) joints. In Zr free alloys, as a result of the high growth rate and steep thermalgradient, the melted layer re-grew with a stable front, epitaxially, from the parent subsurface grains.This caused a thin coarse grained solidified layer to form over the parent material, thermomechanicallyaffected zone (TMAZ) and heat affected zone (HAZ), and fine columnar grains todevelop over the FSW nugget zone of the same order in width as the nugget grain size. In the caseof the Zr containing alloys, a very fine columnar grain structure was found over the entire surface,independent of the subsurface grain structure. This has been shown to occur by growth selectionfrom a band of nanoscale Al grains epitaxially nucleated on Al3Zr dispersoids, at the melt solidinterface, that had not fully dissolved in the melt
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/13/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.519-521.1169.pdf
