Structural, magnetic and magnetostrictive properties of Tb0.2Pr0.8(Fe0.4-xCo0.6+x)1.93 alloys

Structural, magnetic and magnetostrictive properties of Tb0.2Pr0.8(Fe0.4-xCo0.6+x)1.93 (0 ≤ x ≤ 0.2) alloys have been investigated by means of x-ray diffraction, ac initial susceptibility, a superconducting quantum interference device magnetometer and a standard strain gauge technique. A single (Tb, Pr)(Fe, Co)2 Laves phase with a cubic MgCu2-type structure is formed when 0.05 ≤ x ≤ 0.2. Increasing the Co content in the Tb0.2Pr0.8(Fe0.4-xCo0.6+x)1.93 alloys reduces the magnetocrystalline anisotropy constant K1 and improves the magnetostrictive properties at relatively low magnetic fields at room temperature. The Tb0.2Pr0.8(Fe0.35Co0.65)1.93 alloy with a single Laves phase has a spontaneous magnetostriction λ111 as high as 1900 ppm, a large magnetostriction λa (= λparallel - λperpendicular) at a relatively low magnetic field and a large λa/K1, and may make it a promising magnetostrictive material