ISSN:
1662-9779
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Physics
Notes:
Semi-solid processing is nowadays a powerful technology for the realization of structuralcomponents; in addition to the increase in their mechanical properties, due to the globular structureinstead of the dendritic one, further developments are most likely to be expected from alloy chemicalcomposition adjustments in order to achieve higher performances compared with the industrially usedA356 and A357.Aim of this research is to try to set up new aluminium alloys for semisolid foundry applications,starting from the standard Al-Si system, at the base of all known casting processes. Different chemicalcompositions, based on either foundry or wrought Al alloys, have been investigated by means ofcomputational thermodynamics (Pandat®), producing quantitative data about solidus-liquidusinterval, solid fraction as a function of temperature, phase diagrams i.e. potential for age hardening,etc..Some selected alloys, fitting the needs of good castability, proper concentration of hardeningelements in the alpha phase and, obviously, easy production of feedstock material have beenmechanically stirred by means of an experimental apparatus designed and self-constructed in thefoundry laboratory of the university; the effect of different stirring tool configurations on thesemi-solid state obtainment has also been assessed. Subsequently, the manufactured alloys have beenreheated and cast into a simple die, properly designed, for the production of small samples.Microstructural investigations have been done on the stirred alloy (before and after re-heating), on theas cast and the heat treated samples to evaluate the efficiency of the designed system and of thedefined alloys. Experimental tests on the processed alloys have been carried out by means of aninstrumented crucible in order to verify the predicted thermodynamic properties supplied bysimulation study (i.e. fs-temperature curve)
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/22/transtech_doi~10.4028%252Fwww.scientific.net%252FSSP.116-117.58.pdf
Permalink
