DETERMINATION OF THIN FILM'S MECHANICAL PROPERTIES

Both XRD examinations of borided layers show that only FeB phase exists on the surface.But if used SEM, cross-sectional investigation of layers demonstrate that two diffusion layers(FeB and Fe 2 B) in saw-tooth shapes.SEM cross-sectional investigations show that double phase layer from surface to inside ofsubstrate. SEM cross-sectional photograph of SAE 1020 and SAE 1040 quality steels, whichwas borided at 900 o C for 2, 4 and 6h, are shown in Figure 3.3. and Figure 3.4., respectively.The structural compositions of layers consist of boron rich phase (FeB) and iron rich phase(Fe 2 B), respectively. FeB formation begins from surface, Fe 2 B phase forms in deeper regionbecause of decreasing boron concentration form surface to inside of substrate. According tothe SEM photograph, saw tooth microstructural images show both FeB and Fe 2 B phase.a) b)c)Figure 3.3 Borided layer thickness of 1020 steel for different process time SAE 1020 steela) 2 h borided, b) 4 h borided, c) 6 h borided