Abstract
Thin metallic films are a common component of micro-electromechanical systems (MEMS) where they are exposed to different scales of temperatures and mechanical strains.
A common method to prepare nanocrystalline thin films of different thicknesses is via physical vapor deposition. The grain size is an important aspect of the thin film's mechanical properties and is increased with film thickness due to the columnar character of the deposited grains. The further altering of grain size is possible via recrystallization during the heat treatment.
The 50 and 150 nm thick films were prepared by DC magnetron sputtering from a low-carbon steel target. The films were deposited on a polymer substrate, which was then dissolved to obtain free-standing films. The initial microstructure of the films was analyzed by transmission electron microscopy (TEM) equipped with Automated phase and orientation mapping (ACOM-TEM). The films were annealed up to 600oC by in-situ heating in TEM and the microstructure was monitored.
The recrystallization heating of steel films with different grain sizes and film thicknesses was then simulated by molecular dynamics (MD) and the simulated results were compared to the experiment.