考虑膜厚影响薄膜磁致伸缩系数、泊松比和杨氏模量的同时测量

基于经典层合板理论,建立了一个能同时测量薄膜-基底系统中薄膜的磁致伸缩系数、杨氏模量和泊松比的板模型.以前的研究计算薄膜磁致伸缩系数时,大多假设薄膜的弹性属性与相应的块材一致,由此导致的磁致伸缩系数计算是不准确的.在目前大多数方法中仅仅在使用一个单一的弹性各向同性基底中能够避免这个问题.该文模型在各向异性基底下同样适用,并且不要求薄膜的厚度远远小于基底厚度,因此也能够用来计算磁致伸缩应变和设计微电机械系统和生物微电机械系统.对已有的铁基非晶薄膜的实验数据,在不同磁场强度下,磁致伸缩系数的计算结果与已有模型进行了比较,它们之间的差异得到了解释.同时,还可以得到薄膜的弹性常数.

SIMULTANEOUS MEASUREMENTS OF THE MAGNETOSTRICTIVE COEFFICIENT,YOUNG'S MODULUS AND POISSON RATIO OF THE THIN FILM CONSIDERING THE THICKNESS OF FILM

Based on the classical laminated plate theory,a plate model,which determines simultaneously the magnetostrictive coefficient,Young's modulus and Poisson ratio of a thin film of a cantilever film-substrate system,is suggested. An inaccuracy for the magnetostrictive coefficient,caused by assuming the elastic properties of the film as those of the corresponding bulk material,could be avoided and only a single elastic isotropic substrate is employed in the method proposed.The model in this paper is suitable for an anisotropic substrate,and the film thickness is not required far smaller than the thickness of the substrate.So,if the properties of individual layers are known,the plate theory can also be used to determine magnetostriction strain and design multilayer MEMS(microelectromechanical systems) or bio-MEMS(bio-microelectromechanical systems) over a full range of thickness ratios.The experimental data of an Fe-based amorphous thin film were analyzed by using the model.The calculated results of the magnetostrictive coefficient on the external magnetic field was compared with the other existing models,and the discrepancy among these results were explained.At the same time,the elastic properties of the film were also obtained.