ISSN:
1662-9752
Quelle:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Thema:
Maschinenbau
Notizen:
A study of the effect of strontium on some solidification parameters, such as eutecticnucleation temperature, eutectic growth temperature, eutectic undercooling temperature and eutecticundercooling time, has been carried out using thermal analysis for a composite reinforced with 15vol. % SiCP and, for comparison, for an A356 aluminum alloy. The composite is prepared by themelt stirring technique with a SiC particle size of 38 μm. Thermal analysis results show that thepresence of SiCP in the unmodified A356 aluminum alloy increases the eutectic growth temperature(TE) and the eutectic nucleation temperature (TNucl); on the contrary, SiCP decreases the eutecticundercooling temperature ([removed info]θ) and the eutectic undercooling time (tE). These phenomena suggestthat SiC particles give favorable conditions for the growth of eutectic silicon. On the other hand, themodification with strontium of the composite material, although showing basically the same effecton the eutectic parameters as the one described for the A356 aluminum alloy, brings about certaindifferences due to the presence of the SiC particles. Microstructural analysis shows that the eutecticstructures in the composite are coarser than those of the matrix alloy and they do not have theclassic fibrous eutectic shape obtained in the matrix alloy. For the matrix alloy, when the Srconcentration increases beyond the quantity required to obtain a well-modified structure, theeutectic structure suffers a gradual coarsening or a reversion from fine fibrous silicon to coarsersilicon; subsequently, when the Sr concentration is higher than 0.068%, Al2Si2Sr particles areproduced. In the composite material there is also a gradual coarsening of the eutectic structure,although the appearance of Al2Si2Sr particles is just seen when the Sr concentration reaches0.106%
Materialart:
Digitale Medien
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/17/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.560.47.pdf
Permalink
