毕业论文课题相关文献综述
As the most widely used material, metal has been applied to social and industrial infrastructures. But corrosion induced fatigue and failures cause fatal disaster which costs billions of dollars per year in the U.S. alone, and 40% mechanical failure due to corrosion. Corrosion characterization is meaningful for safety of society and industry. Therefore, many nondestructive testing and evaluation (NDTs movement.During domain wall movement, domain wall energy is spent to overcome the pinning sites. The abrupt jumps due to energy spending lead to sudden changes in the magnetization of the material. Even though the applied magnetic field changes smoothly, these so-called Barkhausen jumps are the reasons of the discontinuity that is directly observable in the hysteresis loop.The changes in the magnetization, induce electrical pulses which generate a noise-like signal called Barkhausen noise. Barkhausen noise, the irreversible jumps of domain wall over pinning sites, is called noise because of the sound heard from the speaker used in the original experiment.
