Effect of Chemical Composition on Apparent Viscosity of Semisolid Alloys.

Abstract

,.Chuo-ku.

Measurement and Characterization of the Apparent Viscosity of Fe–C Melts during Solidification

“…P increased with increasing carbon content while f scr decreased with increasing carbon content. Previous study 7) showed that a higher solute concentration in an alloy led to the formation of rosette-type crystals, resulting in particles with relatively large surface areas and irregular, non-spherical shapes. Therefore, the geometrical shape parameter of the crystals "P" became larger with increasing solute concentrations in melts and the volume fraction of liquid trapped between the primary crystals increased, and thus the critical solid fraction, f scr became smaller.…”

“…It was found that the viscosity depended on the solid fraction, the cooling rate, and the shear rate, and the viscosity was influenced more by the cooling rate than the shear rate. Hiral et al 7) quantified the effect of chemical compositions on viscosity of several semi-solid alloys such as Al-Cu, Al-Si, Cu-Sn, and Fe-C (0.8 and 2.5%C). In this research, a uniform predicting model on apparent viscosity was obtained, where the density of alloys (termed as ρ m in that research) was utilized as an important parameter to characterize the effect of chemical compositions on apparent viscosity of semi-solid alloys.…”

“…Happel's model 10) and Thomas's model 11) only consider the influence of the solid fraction without considering the impact of external factors. Currently, the model proposed by Mori and Ototake 12) is most often used to characterize the apparent viscosity of metals in the semi-solid state 7,[13][14][15] (Eq. (1)):…”

“…The Mori and Ototake model considers the effects of the size and shape of the solid particles on the viscosity of the mixture and is applicable over a wide solid fraction range. By using the Mori and Ototake model structure, Hiral et al 7) developed a model for predicting the apparent viscosities of Al, Cu, and Fe-based semi-solid alloys and Matsuzaki et al 13) developed a slag viscosity estimation model with respect to the deposition of the solid phase.…”

“…(2) to simulate the variation in the apparent viscosity in Fe-C melts during solidification, the main parameters P and f scr are primarily influenced by the cooling rate, shear rate and carbon content of the alloy. Hiria et al 7) studied the apparent viscosity of semi-solid Al-10%Cu alloy using Eq. (2) and showed that P and f scr had an exponential relationship with the solidification rate and shear rate.…”