Magnetostriction measurements in Ni alloy single crystals at cryogenic temperatures

Nickel and nickel based magnetostrictive alloys have been used in the many actuator and sensor applications. Though the magnetostrictive values of nickel are not very large, the good mechanical properties of nickel and nickel based alloys make them attractive in various applications. In this work, the effect of Si and Sn addition on the magnetostriction of Ni is examined. Si and Sn belong to the same Group IVA in the periodic table. However atomic size of Si is smaller than Ni and Sn has a larger atomic size compared to Ni. No prior data exist on the influence of Si and Sn addition on the magnetostriction of Ni single crystals. In this work, single crystals of pure Ni, Ni-3.75 at.% Si and Ni-5 at.% Sn single crystals were prepared using vertical Bridgman technique. Single crystal characterization was done using X-ray diffraction. [001] oriented parallelepiped shaped Ni-3.75 at.% Si and Ni-5 at.% Sn single crystals samples and [110] oriented disk sample of Ni single crystals were used to perform magnetostriction measurements. The magnetostriction measurements were performed at room temperature and at temperatures down to 208 K. A cryogenic magnetostriction measurement system capable of measurement at temperatures down to 10 K was designed and set up. The (3/2) X\oo, and (3/2) Xm obtained in nickel single crystals were -87 x 10"6, and -40 x 10"6, respectively, and these values are higher than values reported in literature. For Ni-3.75 at.% Si, (3/2) Xm obtained was -55 x 10"6 and the (3/2) Xm obtained in Ni-5 at.% Sn was -51 x 10"6. For Ni-3.75 at.% Si and Ni-5 at.% Sn, the saturation magnetizations values measured using a vibrating sample magnetometer (VSM) were 33.4 and 17.2 emu/g respectively, compared to a value of 55.9 emu/g observed in Ni. Both Si and Sn addition lead to a decrease in the magnetization and the magnetostriction of Ni. However, on a per atom basis, the drop in magnetostriction is higher with Si addition and the drop in magnetization is higher with Sn addition.