THE 530 ISOTHERMAL SECTION OF THE PHASE DIAGRAM OF Dy-Mn-Ni TERNARY SYSTEM

The 530 isothermal section of the phase diagram of Dy-Mn-Ni ternary system has been investigated by X-ray powder diffraction, DTA, optical microscopy and scanning electron microscopy teckniques. It consists of 13 single-phase regions, 22 two-phase regions and 10?three-phase regions.The 13 single-phase regions are: ot(Dy), x(Mn), ? (Ni),5[B: (DyMn2-DyNi2)], e(Dy6Mn23), O (DyMn,2), y(Dy3Ni), T,(Dy3Ni2), v (DyNi), K(DyNi3), X (Dy2Ni7), u(DyNi5) and I (Dy2Ni,7).The 22 two-phase regions are : a+y, y+T|, TI+VI v+8i 5+K, K+X,, +p, p+x?5, a+5, 5+v,5-H/, 8+n,e+K, and ?%.The 10 three-phase regions are : +p,, , A.+E+K, 5+s+K, 6+v+T|, y+T|+8 and y+5+a. The XRD results confirm that 11 binary compounds, namely Dy2Ni,7,DyNi5, Dy2Ni7 , DyNi3, DyNi2, DyNi , Dy3Ni2 ,Dy3Ni , DyMn2,Dy6Mn23 and DyMni2,exist in this ternary system.Under our present experimental condition, the existence of the compounds DyNi4 and Dy4Nii7 was not observed in Dy-Ni system. The existence of the compounds DyNi4 and Dy4Nii7 was not observed in this ternary system, either. No ternary compound was discovered. Manganese and nickel don't form intermetallic compounds at 530?C.At 530,the maximum solid solubilities of Mn in Ni, Dy2Nii7, DyNi5 , Dy2Ni7, DyNi3, DyNi, Dy3Ni2 and Dy3Ni are about 31 at. % Mn, 6 at.% Mn, 5.5 at. % Mn, 3 at. % Mn, 5 at % Mn, 5 at.% Mn, 3 at.% Mn and 1.5 at.% Mn, respectively. The maximum solid solubilities of Ni in Mn , DyMn^ and Dy6Mn23 are about 2.6 at.% Ni, 2 at.% Ni and 4 at % Ni, respectively.DyMn2 and DyNi2 form a continous solid solution B: ( DyMn2-DyNi2) at 530?C in this system.