Stress evolution in diamond thin film bonded to ductile substrate analyzed by Finite element modeling and micro-Raman spectroscopy

Abstract

In this work, finite element analysis (FEA) has been used to study the effects of hard film thickness, interlayer and its thickness, and residual stresses in the ‘film and interlayer’ on the stress transfer to the film from the substrate under uniaxial tensile loading. Moreover, the successive stress development/evolution in the film, and the deformation mechanism of hard-film/ductile-substrate system have been comprehended. Using FEA, the results of stress evolution in diamond film, acquired from in-situ tensile testing in μ-Raman spectroscope, have been validated. The present results show that thicker films need higher amount of stress transfer from the substrate as compared to thinner films to acquire the same stress level under uniaxial tensile loading. An interlayer reduces the amount of stress transfer to the film. Moreover, the thinner the interlayer the higher will be the stress transfer to the film per unit substrate strain. The presence of residual stress in the interlayer also increases the amount of stress transfer to the film from the substrate. Further, the stress evolution results produced with FEA are consistent with the experimental results of in-situ tensile testing in μ-Raman spectroscope.