Effect of sodium modification on microstructure and mechanical properties of thick-walled AlSi6Cu2.5 rheocast component
The microstructure and tensile properties were investigated in a thick-walled section (approximately 45 mm×43 mm) of a rheocast component produced by the RheoMetalTM process.Due to the long solidification period of such components,it is expected that the Al-Si eutectic formed will be coarse.Therefore,sodium (Na) was used as a modifying agent to reduce the coarseness of the eutectic.Tensile test bars were machined from three different sets of materials:1) non-modified melt,2) modified melt cast directly after Na addition,and 3) modified melt cast 30 min after Na addition.The alloy used was a secondary AlSi6Cu2.5 alloy (STENAL Rheo1),specially developed for rheocasting.The material was studied in the as-cast condition as well as after a T6 heat treatment.The results show that the Al-Si eutectic is significantly refined by the Na addition,even after a fading time of 30 min.However,it is observed that the Na modification generally has a detrimental effect on the mechanical properties,despite the structure refinement.This is especially true in the T6 heat treated condition,where the yield strength is reduced by more than 30％.Some possible mechanisms for the degradation of mechanical performance are discussed.
rheocasting thick-walled component eutectic modification mechanical properties sodium Al alloys
M.WESS(E)N N.E.ANDERSSON O.GRANATH
School of Engineering, Materials and Manufacturing-Casting, J(o)nk(o)ping University, PO Box 1026, SE-55111 J(o)nk(o)ping, Sweden
国际会议
北京
英文
1643-1648
2010-09-16（万方平台首次上网日期，不代表论文的发表时间）