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 early view of superplasticity was that it was a phenomenon that could only be exhibitedby fine grained, two phase alloys. This effectively ruled out most alloys that possessed attractiveservice properties. The first material to demonstrate good superplastic properties from a virtuallysingle phase microstructure was the Al-6%Cu-0.5%Zr, AA 2004 but this was followed bysuperplastic versions of AA7475, AA8090 and AA5083. Superplasticity was also demonstrated inmagnesium based alloys at an early stage.More recently different grain control additions, such as scandium or erbium have been investigatedand it has also been demonstrated that, in certain circumstances, aluminium simply with the additionof a grain controlling element can exhibit good superplastic behaviour. While conventional wisdomteaches that large fabricating strains are required to confer good superplastic properties in the sheetproduct, recent results with both aluminium and magnesium alloys cast doubt on this belief.Although, for many years, strip casting has appeared to provide an attractive semi-fabricating routefor superplastic sheet problems with centre line segregation in alloys with a wide freezing range haveprecluded its use. It has been demonstrated that recent developments in strip casting enableproduction of alloys with as wide a freezing range as AA5182 to be cast with a fine, equiaxed grainstructure across the strip thickness.The paper will review the state of these various developments and their implications for themanufacture of superplastic sheet materials
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/16/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.551-552.357.pdf
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