| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1800378 | Journal of Magnetism and Magnetic Materials | 2011 | 5 Pages |
This study mainly shows that in the Fe66Pd30Rh4 (at%) alloys, the L10 phase plays an important role in magnetostriction due to the interplay of L10 martensitic twins with magnetic domains. The L10 martensitic twin structure exhibits a strong magnetocrystalline anisotropy energy constant (Ku=1.27–2.84×106 (ergs/cm3)) along the tetragonal c axis direction. In addition, the L10 tetragonal martensitic twin structure shows both a perfect shape memory and a reversible shape memory effect; therefore, it is expected to be applicable in magneto-mechanical applications (such as microactuators or springs). However, in this study, we discover that solution treatment (ST) and aging heat treatments of Fe66Pd30Rh4 ferromagnetic shape memory alloys influence the behavior of the martensitic transition, which is associated with the change in magnetic properties. The process of a thermoelastic L10+L1m twin phase decomposition→non-thermoelastic L10+L1m+αbct structure in Fe66Pd30Rh4 alloys during solution treatment and aging at 400–550 °C for various times is studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The relation of phase separation morphology to the magnetic property change is examined with a superconducting quantum interference device (SQUID) magnetometer, and magnetostriction measurement is performed with a strain gage method and magnetostrictive meter setup. The results indicate that the process of martensitic transformation during aging leads to an increase in coercivity and a decrease in magnetostriction, simultaneously.
► Fe66Pd30Rh4 FSM alloys were strain-forged to a ∼40% reduction and solution treated (ST) at 950 °C for 1.5 h. ► L10+L1m martensitic twins contribute a high magnetostriction (λ∥s=80×10−6; λ⊥s=−36×10−6). ► Destruction of the magnetostriction (λ∥s=7×10−6; λ⊥s=–4×10−6).
