Characterization of Shear Deformation Based on In-situ Observation of Deformation in Semi-solid Al–Cu Alloys and Water-particle Mixture

Abstract

In-situ observation of deformation at the grain scale in semi-solid Al-Cu alloys has been carried out using synchrotron X-ray radiography. The deformed microstructure was characterized by the quantitative analysis of solid motion from the image sequences during shear in semi-solid Al-Cu alloys. The influence of solid particle shape on shear deformation was also examined by comparing with in-situ observation of deformation in water-polystyrene particle mixtures where the polystyrene particles are spherical with a diameter of 500 μm. In both semi-solid Al-Cu alloys and water-particle mixtures, solid particles located close to the shear plane developed an increasing component perpendicular to the shear plane, and a relatively high shear strain rate and decreased solid fraction was localized in a shear domain. The shear band width in semi-solid Al-Cu alloys (~10 mean particles diameter) was approximately two times wider than that formed in water-particle mixtures due to the difference in the solid particle shape.

In Situ Observation of Deformation in Semi-solid Fe-C Alloys at High Shear Rate

“…This distribution of the solid vectors is consistent with the previous studies at the low shear rate of 10 À3 /s. [18][19][20][21][22] The rotation angles of solid particles during a 1.2d increment of the push plate motion were examined. Figure 4 shows the rotation field of the 67 solid particles within a 20d width.…”

“…The localization of high shear strain rate at the shear domain with the decreased solid fraction (i.e., a dilatant shear band [1] ) is a common characteristic with the semi-solid deformation at the low shear rate of 10 À3 /s. [18][19][20][21][22] The shear band was defined as the region of coupled localized shear strain and decreased solid fraction, as shown in Figures 11(c) ((e) through (h)) The dilation of the solid particle assembly, where liquid regions between solid particles are defined as white and solid particle boundaries are traced black. The solid particle, labeled A corresponds to that in Fig.…”

“…The overall global shear rate is then 0.8 to 1.5 9 10 À1 /s, which is 100 times higher than that in the previous in situ experiments of semi-solid Fe-C alloys. [18][19][20][21][22] Experiments were carried out at a beamline BL20XU of the SPring-8 synchrotron facility, Hyogo, Japan. The X-ray energy was set to be 21 keV to obtain sufficient solid-liquid contrast.…”

“…[9][10][11][12][13][14][15][16][17] The in situ observations of deformation at the grain scale in semi-solid Al-Cu alloys and carbon steels have been carried out using similar techniques. [18][19][20][21][22] Past research [18][19][20][21][22] showed that shear-induced dilation occurred by grain rearrangement including rotation and translation of solid particles in response to a force chain network at the low shear rate of 10 À3 to 10 À2 /s. Additionally, the quantitative analysis of semi-solid deformation in Al-Cu alloys has confirmed that a relatively high shear strain rate of 10 À2 /s is localized in the shear domain with decreased solid fraction, which corresponds to the shear band.…”

Synchrotron Radiography Studies of Shear-Induced Dilation in Semisolid Al Alloys and Steels

“…28,29 However, direct in situ imaging has shown that semisolid alloys often deform by shear-induced dilation. 23,24,30,31 As an example, Fig. 2c shows a local region of microstructure where the configuration of four grains and the loading direction are similar to the geometry in Fig.…”