Effect of solidifying conditions on the spacing and inclining angle of twin boundaries of feathery crystals in Al-Mg alloys.

Effects of casting parameters on microstructure and dendrite morphology of ZA27 zinc based alloy

“…3a) that the existing investigations have proposed. [5][6][7][8][9][10][11] Figure 3a shows that a laminar dendrite has one primary trunk and two lines of secondary arms, which is completely identical to the structure that has been proposed by the existing investigations. 5,[9][10][11] The difference of the other structured grains with the laminar ones is that they are not a 2D structured laminar form and always have more than two lines of secondary arms, such as three lines (marked by B in Fig.…”

“…[6][7][8] In fact, there are still some disputes for the formation conditions. Lots of investigations supposed that the reason for the effects of the solute elements was that the solutes changed the solid/liquid interface anisotropy and the atom's adsorption kinetics, and thus resulted in the formation of twins and the change of growth direction.…”

“…5,9 Twinned dendrite trunks always grow along ,110. direction and have a highly complex branch morphology of ,110. secondary arms. 5,6 However, their 3D morphology has not been visually observed.…”

Formation of twinned lamellas with the application of static magnetic fields during semi-continuous casting of Al–0.24wt%Fe alloy

“…Moreover, the spacing between columnar trunks in the twinning plane (inplane spacing) is much smaller than the lamellar spacing (interplane spacing). However, the formation mechanism of feathery grains is still not clearly understood despite many years of investigations [4][5][6][7][8][9].…”

“…Columnar grains normally appear in small slabs on condition of approximate one-dimensional (1D) heat transfer and grow roughly perpendicular to the solid-liquid interface. Feathery grains, which are usually undesirable in manufacturing, occasionally occur in aluminum alloy ingots when specific solidification conditions (high temperature gradient at the solidification front, high cooling rate [1], the presence of convection [2] and/or certain alloying elements [3]) are met. It was found that they are made of twinned lamellas with the primary and secondary arms growing in /110S directions [4].…”