Microstructure and thermal stability of amorphous SiBCNAl powders fabricated by mechanical alloying

Amorphous SiBCNAl powders have been prepared by mechanical alloying (MA) technique using crystalline silicon (Si), hexagonal boron nitride (h-BN), graphite (C) and aluminum (Al) as starting materials. Microstructural characterization was carried out by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and selected area diffraction (SAD). The results showed that the MA SiBCNAl powders were completely amorphous and no nanocrystalline structure had been detected. 29Si and 27Al solid-state nuclear magnetic resonance (NMR) spectra have provided evidence that Si and C atoms are intimately mixed at atomic levels and aluminium is present as mixed AlN4, AlN5/AlO4 and AlN6 units. Structural characterization by X-ray photoelectron spectroscopy (XPS) has shown the coexistence of chemical bonds formed by reactions of element of Si, B, C, N and Al. The thermal stability of SiBCNAl powders has been analyzed by thermogravimetry in argon.