The effects of erbium addition on the rheological properties and microstructure of a semisolid A356 alloy were studied.The semisolid slurries were prepared through the serpentine channel technique before they were thi...The effects of erbium addition on the rheological properties and microstructure of a semisolid A356 alloy were studied.The semisolid slurries were prepared through the serpentine channel technique before they were thixoformed using parallel-plate compre ssion with cylindrical discs.The grain and globule size decreases as the Er content increases,resulting in an improved and uniform distribution of spherical primaryα-Al phase within the semisolid slurry.The addition of the Er modifies the grain morphology and size of theα-Al grains,resulting in a better and more uniform distribution of spherical primaryα-AI phase within the semisolid slurry.As a result,rheocast quality index increases with the addition of Er,which is suitable for the thixoforming process.The A356 alloy without Er has the highest viscosity herein.The viscosity decreases,and the flow characteristics of the semisolid feedstock are expected to improve when Er is added as a result of the refinement of primary a-Al and modification of eutectic silicon.Furthermore,the refined semisolid A356 alloys with Er show a slightly larger fraction of highangle grain boundaries compared to that for the unrefined alloy.展开更多
文摘The effects of erbium addition on the rheological properties and microstructure of a semisolid A356 alloy were studied.The semisolid slurries were prepared through the serpentine channel technique before they were thixoformed using parallel-plate compre ssion with cylindrical discs.The grain and globule size decreases as the Er content increases,resulting in an improved and uniform distribution of spherical primaryα-Al phase within the semisolid slurry.The addition of the Er modifies the grain morphology and size of theα-Al grains,resulting in a better and more uniform distribution of spherical primaryα-AI phase within the semisolid slurry.As a result,rheocast quality index increases with the addition of Er,which is suitable for the thixoforming process.The A356 alloy without Er has the highest viscosity herein.The viscosity decreases,and the flow characteristics of the semisolid feedstock are expected to improve when Er is added as a result of the refinement of primary a-Al and modification of eutectic silicon.Furthermore,the refined semisolid A356 alloys with Er show a slightly larger fraction of highangle grain boundaries compared to that for the unrefined alloy.
