Alloying behaviour of zinc with rare earth metals: the Er-Pr-Zn system

Zinc based alloys are among the most commonly used light alloys. To improve the knowledge of the ternary systems constituted by zinc with two lanthanides the isothermal section at 400°C of the Er-Pr-Zn system was studied. Some selected samples at the Er:Pr ratio =1:1 were investigated by differential thermal analysis to draw the vertical section of the system. The experimental techniques used were X-ray powder diffraction (XRPD), scanning electron microscopy (SEM), coupled with electron probe microanalysis (EPMA-EDX) and Differential Thermal Analysis (DTA). No ternary compounds were found in the system. As regard the intermetallic phases, the (Er,Pr)Zn, (Er,Pr)Zn2, (Er,Pr)Zn3, (Er,Pr)13Zn58 and (Er,Pr)2Zn17 solid solutions form in the full field of composition, while the ErZn12, Pr3Zn11 and PrZn11 compounds partially dissolve the third element. The metastable intermetallic binary phases ErZn5, PrZn5 and Er6Zn23 were not found either as ternary solid solutions nor as binary compounds in the ternary Er-Pr-Zn system at 400°C.