Skip to main content
U.S. Department of Energy
Office of Scientific and Technical Information

Structure evolution during semi-solid synthesizing of Al-Si alloys

Book ·
OSTI ID:186751
;  [1]
  1. National Cheng Kung Univ., Tainan (Taiwan, Province of China). Dept. of Materials Science and Engineering
The thixotropic behavior and microstructure evolution of A356 Al-Si alloy in the semi-solid state were investigated. During isothermal stirring, the sphericity increases as the shear rate increases. The grain size decreases and the sphericity increases as the shear rate increases for short stirring time. The grain size increases as temperature decreases during isothermal stirring. Spheroidizing effect is not significant for short stirring time. During isothermal stirring, both the grain size and sphericity increase as the rest time following stirring increases. The coarsening exponent is 3.2, suggesting that the coarsening is controlled by the volume diffusion of the grains. During isothermal stirring, the sphericity increases and the grain size decreases as the stirring time increases. The authors propose that there is a critical stirring time, above which the grain size increases as stirring time, while below which the grain size decreases as stirring time. The effect of up-time on thixotropic behavior is insignificant due to the short up-time studied. Preexisting grain size and sphericity have no significant effects on the thixotropic behavior. The thixotropic behavior is more significant for higher maximum shear rate. There is a minimum maximum-shear-rate, below which no thixotropy phenomenon can be observed.
OSTI ID:
186751
Report Number(s):
CONF-950201--; ISBN 0-87339-316-3
Country of Publication:
United States
Language:
English