The isothermal section at 450°C of the Yb-Pr-Mg system

In the framework of a systematic investigation of the ternary alloys formed by magnesium with two different metals of the rare earth family, data obtained in a study of the Yb-Pr-Mg system are presented. In the isothermal section at 450 degrees C, phases have been identified which are based on the ternary extensions of the binary compounds PrMg, PrMg3, Pr5Mg41 and YbMg2. The PrMg12 compound on the contrary shows very small ternary solid solubility. Two ternary compounds have also been identified: tau(1), (YbxPr1-x)Mg-2(0.15 less than or equal to x less than or equal to 0.48), cF24-MgCu2 Laves type and tau(2), approximate to (YbxPr1-x)Mg-4.5(0.12 less than or equal to x less than or equal to 0.40), cF440-GdMg5 type. The trends of the lattice parameters and the general features of the isothermal section are discussed and compared with those of other magnesium ternary alloys with rare earth elements. The behaviour of the different MeMg2 Laves phases is particularly highlighted. (C) 1999 Elsevier Science Ltd. All rights reserved.