Microstructural evolution and its outcome on the photo induced micro actuation effect and mechanical properties of copper doped Co-Ni-Al FSMA

Abstract

In this work, we studied the effect of doping with copper to seek improvement in mechanical and photo induced micro actuation (PIMA) properties of a Co-Ni-Al ferromagnetic shape memory alloy (FSMA). Unique and unexplored PIMA property of FSMA system has opened up the scope of various laser controlled micro-mechanical engineering applications in miniature scale. Transmission Electron Microscopy and X-ray diffraction technique were used to characterize and correlate the evolved microstructure with the corresponding changes in the PIMA and mechanical properties. Magnetic properties of these samples were studied by performing hysteresis experiments at room temperature. It was found that partial substitution of cobalt with copper resulted in samples with lower magnetic and PIMA properties but better mechanical property, however, in case of substituting aluminum, it resulted in improvement of the ferromagnetic property but destroyed the PIMA effect altogether. In order to understand these properties changes, the electron density of each of the samples was calculated and compared. These studies should help in deciding on use of new alloys with optimization of PIMA and mechanical property for desired and customized engineering applications.