This paper is aimed at to discuss two cases of active composites, (i) ferromagnetic shape memory alloy composites, and (ii) piezoelectric ceramic-shape memory alloy composites. Here we discuss the merits of designing such active composites, for use as possible actuator materials. To optimize the nano-/micro-structures of such composites, we developed analytical models based on Eshelby type modeling. Based on the modeling study; a few cases of optimized active composites are suggested.
Ferromagnetic Shape Memory Alloy (FSMA) particulate composites are processed using Spark Plasma Sintering (SPS) with various weight fractions of NiTi (51 at% Ni) and Fe powders. Various processing conditions are experimented to obtain the optimum heating rate, holding time and holding temperature in order to maximize relative density, superelasticity and magnetic saturation of the composite. Mechanical strength is evaluated using compression tests.
Ferromagnetic Shape Memory Alloy (FSMA) particulate composites are processed using Spark Plasma Sintering (SPS) with various weight fractions of NiTi (51 at% Ni) and Fe powders. The magnetic properties of these composite specimens were experimentally evaluated using Vibration Sample Magnetometry (VSM). A model for calculating the effective magnetic properties has been presented in this work where Eshelby's inhomogeneous inclusion method considering Mori-Tanaka's mean field theory for larger concentrations of Fe has been used to predict the effective magnetic properties. The analytical results thus obtained are compared with experimental data resulting in a reasonably good agreement.