PECULIARITIES OF THE INTERACTION OF YTTERBIUM WITH TRANSITION-METALS (CR,MN) AND ALUMINUM

The isothermal sections of the Yb-(Cr,Mn)-Al phase diagram at 770 K ha ve been constructed from X-ray powder diffraction phase analysis of ar c-melted and annealed alloys. The Cr-based system contains three terna ry compounds, YbCr2Al20 (CeCr2Al20 structure type), Yb6C4+xAl43-x (x=1 .76, new structure type) and YbCrxAl12-x (x=2.60-4.30, ThMn12 structur e type), while the Mn-based system contains only two, YbMnxAl12-x (x=2 .86-4.55, ThMn12 structure type) and Yb6Mn4+xAl43-x (x=1.76, Yb6Cr4+xA l43-x structure type). The immiscibility range between Yb and the tran sition element decreases more rapidly with increasing Al content in th e Mn system than in the Cr system.