Magnetoelastic properties in polycrystalline ferromagnetic shape memory Heusler alloys

MAGNETOELASTIC COUPLING IN NiMnGa FERROMAGNETIC SHAPE MEMORY ALLOY

Title of Document: MAGNETOELASTIC COUPLING IN NiMnGa FERROMAGNETIC SHAPE MEMORY ALLOY Peng Zhao, Doctor of Philosophy, 2006 Directed By: Professor, Manfred Wuttig, Department of Materials Science and Engineering NiMnGa alloys have attracted extensive attention because their ferromagnetic characteristic provides an additional degree of freedom to control both the shape memory effect and the mult...

Direct evidence of detwinning in polycrystalline Ni-Mn-Ga ferromagnetic shape memory alloys during deformation

Cobalt-base ferromagnetic shape memory alloys

Single crystalline and polycrystalline CoxNiyGa100-(x+y), 41<xCo<62 and 19.3<xNi<32.7 [at%], Ferromagnetic Shape Memory Alloys (FMSMAs) have been produced in the range of the Heusler-type composition. Elasto-mechanical properties have been analyzed for the annealed and quenched states, respectively. The mechanical spectroscopy data show the occurrence of martensitic phase transformations with t...

Finite-element-simulations of polycrystalline shape memory alloys

Shape memory alloys (SMA) are widely employed as sensors and actuators. The need for precise control requires reliable modeling techniques involving, e.g., prescribed stresses and temperatures. These parameters are always inherently coupled in SMA. Various models are in use to characterize the non-linear hysteretic behavior of SMA; among them some that do not provide a means to incorporate true...

Effects of Annealing on the Martensitic Transformation of Ni-Based Ferromagnetic Shape Memory Heusler Alloys and Nanoparticles

We report on the effects of annealing on the martensitic phase transformation in the Ni-based Heusler system: Mn50Ni40Sn10 and Mn50Ni41Sn9 powder and Co50Ni21Ga32 nanoparticles. For the powdered Mn50Ni40Sn10 and Mn50Ni41Sn9 alloys, structural and magnetic measurements reveal that post-annealing decreases the martensitic transformation temperatures and increases the transition hysteresis. This m...