Nucleation of the Primary Al Phase on TiAl 3 during Solidification in Hot-Dip Zn-11%Al-3%Mg-0.2%Si-Coated Steel Sheet * 1

The solidification structure of a hot-dip Zn-11%Al-3%Mg-0.2%Si coated steel sheet with a slight Ti addition was investigated by EBSD. In every center of the primary Al phase of the alloy-coating layer, TiAl 3 was observed by a scanning electron microscope, which suggests that TiAl 3 acts as a heterogeneous nucleation site of the primary Al phase. The latter was revealed to have perfect lattice coherency with the nucleus TiAl 3 phase. The crystal orientation relationships between TiAl 3 and the primary Al are ð001Þ TiAl3 == ð001Þ Al and ½100 TiAl3 == ½100 Al , ð100Þ TiAl3 == ð001Þ Al and ½001 TiAl3 == ½100 Al , ð102Þ TiAl3 == ð110Þ Al and ½ 2 201 TiAl3 == ½ 1 110 Al , ð110Þ TiAl3 == ð110Þ Al and ½ 1 110 TiAl3 == ½ 1 110 Al , indicating that the primary Al phase grows in an epitaxial manner from the nucleus TiAl 3 phase. The planar disregistry between the two phases was calculated to be less than 5%, owing to this good lattice coherency. The TiAl 3 phase is considered to decrease the degree of undercooling necessary for the nucleation of the primary Al phase

Advances in research on deformation and recrystallization for the development of high-functional steels

In order to exploit full potential of materials, it is necessary to fundamentally control their microstructures through grain refinement and orientation. Deformation and recrystallization are means to control the microstructure. Some recent examples of research on deformation and recrystallization which make use of advanced analytical techniques and computational materials science are examined and current limitations are identified. Finally, the potential for future developments is considered with respect to the unresolved technical problems that must be addressed as part of the development of new steels