Phase relations in the Nd–Al–Si system at 500°C

Abstract

The partial isothermal section of the phase diagram of the Nd–Al–Si ternary system at 500°C (50 at.% Nd or less) has been investigated by X-ray diffraction analysis, differential thermal analysis, scanning electron microscopy and electron micro-probe analysis. The existence of six binary compounds, αNd 2Si 3, βNdSi x ( x⩽1.8⩽2.0), NdAl, NdAl 2, NdAl 3 and αNd 3Al 11, and three ternary compounds, NdAl 2Si 2 ( γ), NdAl 1.75Si 0.25 ( δ), NdAl 1.25Si 0.25 ( η), was confirmed. The ternary compound NdAl 1.5Si 0.5 was not found in this section. This isothermal section consists of 11 single-phase regions, 21 two-phase regions and 11 three-phase regions. The compound NdAl 1.25Si 0.25 has a large homogeneity range, while the other ternary compounds are non-solubility compounds.