It has been postulated that, with tensile loading conditions, micro-cracks onthin hard film act as stress concentrators enhancing plastic deformation of the substrate materialin their vicinity. Under favorable conditi...It has been postulated that, with tensile loading conditions, micro-cracks onthin hard film act as stress concentrators enhancing plastic deformation of the substrate materialin their vicinity. Under favorable conditions the localized plastic flow near the cracks may turninto macroscopic plastic strain thus affects the plasticity behaviors of the substrate. Thisphenomenon is analyzed quantitatively with finite element method with special attention focused onthe analysis and discussion of the effects of plastic work hardening rate, film thickness and crackdepth on maximum plastic strain, critical loading stress and the size of the local plasticdeformation zone. Results show that micro-cracks on thin hard film have unnegligible effects on theplasticity behaviors of the substrate material under tensile loading.展开更多
A method for hardness measurement and evaluation of thin films on the material surface was proposed. Firstly, it is studied how to obtain the force indentation response with a finite element method when the indentati...A method for hardness measurement and evaluation of thin films on the material surface was proposed. Firstly, it is studied how to obtain the force indentation response with a finite element method when the indentation is less than 100 nanometers, in which current nanoindentation experiments have not reliable accuracy. The whole hardness indentation curve and fitted equation were obtained. At last, a formula to predict the hardness of the thin film on the material surface was derived and favorably compared with experiments.展开更多
基金This project is supported by National Natural Science Foundation of China(No.59705009).
文摘It has been postulated that, with tensile loading conditions, micro-cracks onthin hard film act as stress concentrators enhancing plastic deformation of the substrate materialin their vicinity. Under favorable conditions the localized plastic flow near the cracks may turninto macroscopic plastic strain thus affects the plasticity behaviors of the substrate. Thisphenomenon is analyzed quantitatively with finite element method with special attention focused onthe analysis and discussion of the effects of plastic work hardening rate, film thickness and crackdepth on maximum plastic strain, critical loading stress and the size of the local plasticdeformation zone. Results show that micro-cracks on thin hard film have unnegligible effects on theplasticity behaviors of the substrate material under tensile loading.
基金Chinese Academy of Sciences Foundation (KGCX1-11) National Natural Science Foundation of China(10 2 3 2 0 5 0 ) Min-istry of Science and Technology Foundation(2 0 0 2 CB412 70 6)
文摘A method for hardness measurement and evaluation of thin films on the material surface was proposed. Firstly, it is studied how to obtain the force indentation response with a finite element method when the indentation is less than 100 nanometers, in which current nanoindentation experiments have not reliable accuracy. The whole hardness indentation curve and fitted equation were obtained. At last, a formula to predict the hardness of the thin film on the material surface was derived and favorably compared with experiments.
