The interface adhesion strength(or interface toughness)of a thin film/substrate system is often assessed by the micro-scratch test.For a brittle film material,the interface adhesion strength is easily obtained through...The interface adhesion strength(or interface toughness)of a thin film/substrate system is often assessed by the micro-scratch test.For a brittle film material,the interface adhesion strength is easily obtained through measuring the scratch driving forces.However,to measure the interface adhesion strength(or in- terface toughness)for a metal thin film material(the ductile material)by the micro- scratch test is very difficult,because intense plastic deformation is involved and the problem is a three-dimensional elastic-plastic one.In the present research,using a double-cohesive zone model,the failure characteristics of the thin film/substrate system can be described and further simulated.For a steady-state scratching pro- cess,a three-dimensional elastic-plastic finite element method based on the double cohesive zone model is developed and adopted,and the steady-state fracture work of the total system is calculated.The parameter relations between the horizontal driving forces(or energy release rate of the scratching process)and the separation strength of thin film/substrate interface,and the material shear strength,as well as the material parameters are developed.Furthermore,a scratch experiment for the Al/Si film/substrate system is carried out and the failure mechanisms are explored. Finally,the prediction results are applied to a scratch experiment for the Pt/NiO material system given in the literature.展开更多
The ductility of thin metal films on polymer substrates reported in recent experiments has a huge disparity,ranging from less than 1 % up to more than 50 %.To reveal the underpinning origins for such a large variation...The ductility of thin metal films on polymer substrates reported in recent experiments has a huge disparity,ranging from less than 1 % up to more than 50 %.To reveal the underpinning origins for such a large variation,this paper reports a systematic computational study of two competing failure mechanisms:metal film necking and grain boundary cracking.The quantitative results suggest that strong grain boundaries and metal/polymer interfacial adhesion are keys to achieve high ductility of polymer-supported metal films.展开更多
基金The project supported by the National Natural Science Foundation of China (19891180 and 19925211)Bai Ren Plan of CAS
文摘The interface adhesion strength(or interface toughness)of a thin film/substrate system is often assessed by the micro-scratch test.For a brittle film material,the interface adhesion strength is easily obtained through measuring the scratch driving forces.However,to measure the interface adhesion strength(or in- terface toughness)for a metal thin film material(the ductile material)by the micro- scratch test is very difficult,because intense plastic deformation is involved and the problem is a three-dimensional elastic-plastic one.In the present research,using a double-cohesive zone model,the failure characteristics of the thin film/substrate system can be described and further simulated.For a steady-state scratching pro- cess,a three-dimensional elastic-plastic finite element method based on the double cohesive zone model is developed and adopted,and the steady-state fracture work of the total system is calculated.The parameter relations between the horizontal driving forces(or energy release rate of the scratching process)and the separation strength of thin film/substrate interface,and the material shear strength,as well as the material parameters are developed.Furthermore,a scratch experiment for the Al/Si film/substrate system is carried out and the failure mechanisms are explored. Finally,the prediction results are applied to a scratch experiment for the Pt/NiO material system given in the literature.
基金supported by the Ralph E. Powe Jr. Faculty Award from Oak Ridge Associated Universities,Minta-Martin Foundation and US National Science Foundation(0856540,0928278)A. J. Clark Fellowship and UMD Clark School Future Faculty Program
文摘The ductility of thin metal films on polymer substrates reported in recent experiments has a huge disparity,ranging from less than 1 % up to more than 50 %.To reveal the underpinning origins for such a large variation,this paper reports a systematic computational study of two competing failure mechanisms:metal film necking and grain boundary cracking.The quantitative results suggest that strong grain boundaries and metal/polymer interfacial adhesion are keys to achieve high ductility of polymer-supported metal films.
