科研之友
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摘要
We analyze the surface morphological stability of bulk conducting face-centered cubic (fcc) crystalline solids in uniaxial tension under the simultaneous action of an electric field and a temperature gradient. The analysis is based on self-consistent dynamical simulations, in conjunction with linear stability theory, according to a well validated fully nonlinear surface mass transport model that accounts for surface electromigration and thermomigration induced by the externally applied fields, surface diffusional anisotropy, and the Arrhenius temperature dependence of surface diffusivity. Our simulation results validate the findings of linear stability theory and establish that the electric field and the thermal gradient, if properly directed, can work synergistically to stabilize the planar surface morphology against the Asaro-Tiller/Grinfeld (ATG) instability when the strength of the resulting effective external field is higher than a critical level. We also show that the temperature dependence of the surface diffusivity does not change the criticality criterion for surface stabilization but only affects the rate of growth or decay of the surface morphological perturbation from its planar state. Furthermore, we establish that, in fcc crystals, the morphological response of < 111 >-oriented surfaces is superior to that of differently oriented surfaces. In case of failure due to ATG instability, the super-exponential growth of the surface perturbation amplitude exhibits a logarithmic singularity as the time to failure is approached. Our study provides an effective practical solution to inhibit the surface cracking of crystalline conducting solids based on the optimal combination of the simultaneous action of externally applied electric fields and thermal gradients.
- 出版日期2014-11-7
