材料期刊网

采用区熔定向凝固方法, 以480 mm/h速度制备了<110>取向Tb_0.36Dy_0.64(Fe_0.85Co_0.15)₂合金棒. 通过测试在0---0.325 T磁场范围内合金 棒的应力--应变回线, 计算了应力幅σ_m分别为-10,-30和-50 MPa的阻尼系数Δ W/W. 结果表明, 零磁场下的Δ W/W最大; 随磁场强度增大, 同一σ_m条件下的Δ W/W逐渐降低. 在低磁场中, Δ W/W随σ_m的增加而降低; 在高磁场中,  Δ W/W随σ_m的增加而升高. 利用不同预压应力下的磁致伸缩--磁化强度关系曲线, 分析了磁场--应力复合加载条件下非180°磁畴和畴壁的运动形式. 依据局部内应力理论, 解释了合金棒的磁机械阻尼系数随外磁场强度和应力幅值变化的规律.

During the mechanical loading and unloading process, Tb--Dy--Fe giant magnetostrictive materials can dissipate a mass of elastic energy due to the irreversible movements of non--180° domain walls, which is of interest to be applied in passive damping control systems. The magnetomechanical damping capacity of Tb--Dy--Fe compound is strongly sensitive to the stress magnitude as well as the external magnetic fields. As a new member of the Tb--Dy--Fe family, quaternary Tb_0.36Dy_0.64(Fe_0.85Co_0.15)₂compound has been developed as a good candidate in wide operating \temperature range applications. In order to realize the application of Tb_0.36Dy_0.64(Fe_0.85Co_0.15)₂ compound in passive damping control system, it is important to systemically investigate its damping capacity under coupled magnetomechanical loadings. In the present work, <110> oriented Tb_0.36Dy_0.64(Fe_0.85Co_0.15)₂ crystal was prepared with a growth velocity of 480 mm/h by zone melting directional solidification method. The damping capacity was studied by quasi--static stress--strain measurements under a series of constant magnetic fields up to 0.325 T. Stress ranges from 0 to -10, -30 and -50 MPa were used at room temperature. The results show that maximum damping capacity (Δ W/W) is obtained at zero field. Under certain stress amplitude σ_m, Δ W/W decreases with the increase of magnetic field. A critical magnetic field exists in the damping capacity--magnetic field (Δ W/W--H) curves, and seems independent on the stress magnitude. Under coupled magnetic--stress loadings, the magnetostriction--magnetization curves were measured to analyze the switching process of domains and movements of domain walls, by which an explanation on the variation of damping capacity was given.