The 500 °C Isothermal Section of the Al-Co-Nd Ternary System

The Al-Co-Nd isothermal section at 500 C has been investigated in the whole composition range by means of x-ray diffraction, optical and scanning electron microscopy and electron probe microanalysis. The following ternary phases have been identified or confirmed: s1-Nd4 CoAl (cF96-Gd4RhIn), s2-NdCo2Al8 (oP44-CeFe2Al8), s3-NdCo3Al11 (unknown), s4-Nd2Co3Al9 (oS56-2Co3Ga9) s5-Nd5Co2Al2 (unknown), s6-Nd2Co6Al19 (mS108 U2Co6Al19), s7-Nd7Co6Al7 (tP40-Pr7Co6Al7), s8-Nd2Co 2Al(oI10-W2CoB2), s9-Nd13Co14-xAl4?x (0 B x B 0.7, oS28-W3CoB3). The complex system of phase equilibria linking the large number of binary and ternary Al-Co-Nd phases at 500 C has been completely determined. The general characteristics of the section have been discussed in comparison with those of other Al-Co-R systems.