Structural features of intermetallic phases in the Ca-Zn-Al system

摘要

The Ca-Zn-Al system has been investigated inthe region from 8 to 33 at% Ca. The results show that thefollowing phases are solid solutions based on the correspond-ing known binary compounds: Ca(Zn_(1-x)Al_x)_3(x =0-0.23,CaZn3 type), Ca(Zn (x = 0.47-1.00, BaA14 type),Ca; _y(Zn ; ,Alx)5+2y (x = 0-0.12 and y = 0 —0.12, CaCu5-derived TbCu7 type), Ca(Zni,A1x); = 0-0.018, BaCd ; ;type), while the phase Ca2(Zni,Alx)17 (x = 0.05-0.17,Th2Zn 17 type) exists with a ternary composition only. Inall pseudobinary systems the cell volume generally in-creases with increasing Al content, as expected for thehigher atomic volume of Al compared with Zn. A substi-tution of Al for Zn is generally observed, but preferentialoccupations, namely different Al/Zn ratio values, occur fordifferent crystallographic sites. This phenomenon givesrise to anomalous trends in the variations of the latticeparameters.