Analysis of Microscale Heat Transfer and Ultrafast Thermoelasticity in a Multi-Layered Metal Film

The micro-scale heat transfer and ultrafast thermoelasticity of a gold-chromium film subjected to ultra-short pulse laser heating is investigated. To predicate the thermal response accurately, the ballistic motion and hot electron diffusion are adopted in the laser source term. The ultrafast thermoelasticity (UTE) model with the modified laser heat source is applied to solve ultrafast thermoelastic behaviors inside a two-layered thin-film and the effect of the contact conductance on the thermo-elastic fields is included in the analysis. It is found that the excessive concentration stress appears at the interface due to the contact conductance effect. Therefore, the mechanical failure or damage may occur at the interface during the very early stage of the heating process even though the thermal resistance is extremely small (as small as 10⁻⁷ m²K/W).