The scanning electron acoustic microscopy investigation on ferroic materials under local stress

摘要

In this paper, the responses in the microregion of three ferroic-type materials, such as ferroelectric single crystals (PMN-PT and BaTiO_3), ferromagnetic alloy (Fe_(81)Ga_(19)), and ferroelastic alloy (Ni_(53)Mn_(24)Ga_(23)), to local stress induced by Vickers indentations were studied using scanning electron-acoustic microscopy (SEAM), a powerful technique for nondestructive investigation of the microstructure of materials. The responses of ferroelectric domains, magnetic domains, and ferroelastic domains to local stress were successfully observed. These responses possess three major features including the plastic deformation underneath the indenter, the extension of microcracks induced by indentation, and the formation of new lamellar domains within the matrix domain structure. In addition, by using the unique ability of SEAM to image layer by layer, the distributions of residual stress at different depths were obtained. The generation mechanisms of the electron acoustic signals of ferroelectric domains, magnetic domains, and ferroelastic domains are discussed.