Can I tear apart a pipe with magnetostriction? And how big field should I use? As I know, with magnetostriction we can "stretch" its unit cell. The stronger is the field, the more it expands the cell. Using alternating current in coils that induce magnetic field we can stretch it and compress it quickly generating sound that travels through the pipe.
How big field should I use to stretch unit cells beyond their Ultimate tensile strengt?
How to determine such field? Where should I dig for data? Or maybe it is impossible?
 A: To tear something apart outright by magnetostriction is, as far as I know, impossible for the following reason: all magnetic materials saturate, i.e. their domains become fully aligned as the magnetic field increases. Further increase of the magnetic field cannot align the domains any better than they are, so no further increase in magnetostrictive strain and stress results from an increased magnetic field. At magnetisation saturation, the maximum magnetostrictive strain is far below that needed to tear or break the material. For example, the saturation magnetostrictive strain of cobalt is about $6\times10^{-5}$ (see "Magnetostriction" Wiki page for source), and its Young's modulus is about $200{\rm GPa}$. This implies a saturation magnetostrictive stress of $12{\rm MPa}$, which is well below its tensile strength, which is at least $200{\rm MPa}$ (see here)
Certainly a transformer has to be designed as a significant load bearing machine as well as being an electrical transformer, and long term damage can result from magnetostrictive forces and forces between currents if this design is not done properly.
