Martensitic Magnetomechanical Measurements
Ni2MnGa Martensitic Magnetomechanical Measurements
The magnetomechanical experiments addressed two main goals of interest for FSM materials:
- Develop a strategy to maximize the field-induced strain and work output related to the
FSM effect
- Investigate the effects of specimen geometry, applied stress, and microstructure bias
on the FSM effect
The strategy for the tests is outlined in the figure below. Specimens were rectangular bars with
<100> edges. In the following discussion, the term axial refers to the long <100> axis of the bar
to which stress is applied, and transverse refers to the short <100> axis along which the field
is applied. Initially, an axial stress is applied to bias a single variant state consisting of the
axial variant (top fig). Then a transverse field is applied to introduce the transverse variant (middle fig). At large fields, the transverse variant dominates, resulting in a large shape change and work
performed against applied load s (bottom fig). By switching between
the two single variant states, the largest possible shape change is realized, and the specimen
geometry allows the applied field to be aligned with the most favorable direction.
To investigate the effects of specimen shape, 3 different aspect ratio specimens were used in
3 series of experiments. For each specimen a series of strain vs. field curves
was performed at a set of increasing applied load values up to the blocking stress.
The original compression specimen CS1-1 was subsequently cut down in size between series
to create specimens CS2-1 and CS3-1.
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Specimen Dimensions |
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