Abstract
Rapid-solidified ferromagnetic shape memory Fe-30.2 at. %Pd alloy ribbon has a large magnetostriction more than 1.0 × 10−3 (= 1000 μ-strain). This type of magnetostriction is caused by the re-arrangements of martensitic twins (i.e., variants) by the applied magnetic field, therefore, it is generally very sensitive to the crystalline texture and twin's morphology of material. In order to develop a more high performance magnetostrictive actuator material driven by smaller magnetic field, the effect of grain and twin boundary microstructures on megnetostriction was studied by changing the condition of heat treatments. For the sample with strongly (100) textured grains after oil-bath quenching, a steep increment and large strain of 0.7 × 10−3 was induced at a fairly low magnetic field of 35 k A·m−1 (= 1.5 kOe) when the magnetic field was applied normal to the ribbon surface. On the other hand, for the sample with randomly oriented grains and excessive existence of twin boundaries by ice-water quenching after long time annealing, the induced strain was initially small and then it gradually increased up to 0.6 × 10−3 at 70kA·m−1. This difference of sensitivity in magnetostriction behavior is discussed from the viewpoint of magnetic domain mobility in connection with grain and twin boundary microstructures.
