Structure and magnetic and magnetostrictive properties of (Tb0.7Dy0.3) Pr-0.7(0.3) (Fe1-xCox) (1.85) (0 <= x <= 0.6)

Measurements of the structure, magnetic properties, and magnetostriction we re made on are-melted polycrystalline (Tb0.7Dy0.3)(0.7)TPr0.3(Fe1-xCox)1.13 5 (0 less than or equal to x less than or equal to 0.6) alloys by X-ray dif fraction, initial susceptibility, vibrating sample magnetometry, and standa rd strain gauge techniques. The measurements showed that the matrix of (Tb0 .7Dy0.3)(0.7)Pr-0.3(Fe1-xCox)(1.85) predominantly consists of the MgCu2-typ e cubic Laves phase, with a small amount of PuNi3-type and rare-earth rich phases. The amount of (Tb, Dy, Pr)(Fe, Co)(2) in (Tb0.7Dy0.3)(0.7)Pr-0.3(Fe 1-xCox)(1.85) increases with increasing Co concentration and becomes almost the only phase present when x greater than or equal to 0.4. The lattice pa rameter decreases approximately linearly with increasing x from 0.7357 nm w hen x = 0 to 0.7300 nm when x = 0.6. The Curie temperature increases with i ncreasing x from 640 K when x = 0 to 677 K when x = 0.3, and then decreases to 572 K when x = 0.6. The saturation magnetization M-s exhibits a minimum near x = 0.3. The polycrystalline magnetostriction of (Tb0.7Dy0.3)(0.7)Pr- 0.3(Fe1-xCox)(1.85) decreases monotonically with increasing x. There is no evidence of an anomalously large lambda (100) value as is the case for othe r R(Fe1-xCox)(2) compounds.