The ternary Ni-P-W coatings containing scattered Nb₂O₅particles were deposited on the sintered NdFeB substrates by electroless plating. The effect of experimental processing parameters on the deposition rate was investigated during electroless plating. The coatings performance, such as corrosion resistance, interfacial adhesion strength and micro-hardness, was evaluated by experimental testing. The experimental results indicated that the corrosion resistance of Ni-P-W/Nb₂O₅ composite and the interfacial adhesion strength between Ni-P-W/Nb₂O₅coatings and NdFeB substrate have been increased with increasing the Nb₂O₅ concentration up to 15gL^-1. Increasing Nb₂O₅ concentration over 15gL^-1decreases the corrosion resistance of Ni-P-W/Nb₂O₅composite and the interfacial adhesion strength. Testing of micro-hardness showed that the hardness of Ni-P-W coatings containing scattered Nb₂O₅ composite increases with increase in Nb₂O₅ concentration.

The effect of external strain on the non-linear electromechanical behavior of a ferroelectric poly-crystal is investigated under different applied electric fields by using a phase field model. Simulation results show that the domain switching induced by electric field under a tensile strain is much easier than that under a compressive strain, which is attributed to that a multi-domain structure can be more easily formed under the tensile strain than in the case of compressive strain when the electric field is absent. It is also found that a compressive misfit strain increases the macroscopic coercive field and remnant polarization while a tensile misfit strain decreases both of them. In addition, a compressive strain decreases the non-linear dielectric constant while a tensile strain increases it.