Figure 4: Determination of amorphous carbon and a-B4C at interface region using STEM.
From: Enhanced mechanical properties of nanocrystalline boron carbide by nanoporosity and interface phases
(a) High-resolution STEM image from indented region at 1,000-mN applied force, showing a wide amorphous interface layer between two B4C grains; Scale bar, 5 nm; and (b) EELS spectra taken from the grain and GB regions (marked as A and B), confirming the amorphous interfacial phase is amorphous carbon (a-C) (red curve) and crystalline B4C (black curve). (c) High-resolution STEM image showing a narrow amorphous interface layer with a width of ~1.4 nm; Scale bar, 2 nm; and (d) EELS spectra taken from both grain and GB areas (marked as C and D), demonstrating the narrow amorphous interfacial phase is amorphous B4C (red curve) with boron and carbon ratio close to that of crystalline B4C (black curve).
