The structure and magnetostriction of (Tb1-xNdx)(Fe0.4Co0.6)1.9 (0≪x≪1) alloys have been investigated at room temperature and the magnetic properties determined over the temperature range 1.5-300 K. It was found that the matrix of (Tb1-xNdx)(Fe0.4Co0.6)1.9 is essentially that of a (Tb,Nd) (Fe,Co)2 phase with a MgCu2-type cubic Laves structure for all values of x. The lattice parameter of the Laves phase increases from 0.7297 to 0.7363 nm as x increases from 0 to 1 and obeys Vegard's law. We have measured the Curie temperature to decrease with increasing x from 667 K for Tb(Fe0.4Co0.6)Fe1.9 to 454 K for Nd(Fe0.4Co0.6)Fe1.9. The resultant macroscopic magnetization becomes zero when x=0.45 at a temperature of 1.5 K. At 300 K, a slightly smaller value of x is found to produce no resultant magnetization, and the spontaneous magnetostriction constant λ111 decreases slowly with increasing Nd content and vanishes abruptly from a value of 1630×10-6 when x≫0.65. The polycrystalline isofield magnetostriction curves exhibit a minimum at x=0.45 and a peak at x=0.65. The observed behavior can be explained on the basis of opposing rare-earth Tb and Nd moments and an anisotropy minimum close to x=0.65. As the temperature is reduced below 300 K, the spin reorientation occurs at greater Nd concentrations.
|Number of pages||5|
|Journal||Journal of Applied Physics|
|Publication status||Published - 1 Dec 1999|