Tb-Al-Si systems: experimental study of the liquid-solid phase equilibria in the Al-rich corner

There are presently limited information regarding the liquid–solid equilibria at the (Al)-rich region of the different R–Al–Si systems (R = rare earth elements). These data, along with the ternary systems isothermal section, are needed to outline the design, plan and develop new Al–Si-based alloys. The effect of the lanthanide terbium addition to the Al–Si system, in the Al-rich corner, has been experimentally studied. The constitution of the alloys and the liquidus surface projection have been determined by means of differential thermal analysis, scanning electron microscopy, electron microprobe analysis and X-ray powder diffraction. In the system investigated have been identified five regions of primary crystallization: TbAl(3 − x)Six, Tb2Al3Si2, TbAlxSi2 − x, (Al) and (Si).