R–Al–Si systems (R: Pr, Nd): Experimental investigation of phase equilibria in the Al-rich corner

The effect of the two light rare earths Pr and Nd 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 two systems investigated have been identified, respectively, six regions of primary crystallization [αPr3Al11, PrAl(1−x)Si(1+x), PrAl2Si2, βPrAlxSi2−x, (Al) and (Si)] for R = Pr and four [NdAl(1−x)Si(1+x), NdAl2Si2, (Al) and (Si)] for R = Nd.