An AI2O3-TiB2 nanocomposite was success- fully synthesized by the high energy ball milling of A1, B2O3 and TiO2. The structures of the powdered particles formed at different milling times were evaluated by X-ray diffr...An AI2O3-TiB2 nanocomposite was success- fully synthesized by the high energy ball milling of A1, B2O3 and TiO2. The structures of the powdered particles formed at different milling times were evaluated by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. Thermo- dynamic calculations showed that the composite formed in two steps via highly exothermic mechanically induced self-sustaining reactions （MSRs）. The composite started to form at milling times of 9-10 h but the reaction was not complete. The remaining starting materials were consumed by increasing the milling time to 15 h. The XRD patterns of the annealed powders showed that aluminum borate is one of the intermediate products and that it is consumed at higher temperatures. Heat treatment of the 6-h milled sample at l l00℃ led to a complete formation of the composite. Increasing the milling time to 15 h led to a refining of the crystallite sizes. A nanocomposite powder with a mean crystallite size of 35-40 nm was obtained after milling for 15 h.展开更多
文摘An AI2O3-TiB2 nanocomposite was success- fully synthesized by the high energy ball milling of A1, B2O3 and TiO2. The structures of the powdered particles formed at different milling times were evaluated by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. Thermo- dynamic calculations showed that the composite formed in two steps via highly exothermic mechanically induced self-sustaining reactions （MSRs）. The composite started to form at milling times of 9-10 h but the reaction was not complete. The remaining starting materials were consumed by increasing the milling time to 15 h. The XRD patterns of the annealed powders showed that aluminum borate is one of the intermediate products and that it is consumed at higher temperatures. Heat treatment of the 6-h milled sample at l l00℃ led to a complete formation of the composite. Increasing the milling time to 15 h led to a refining of the crystallite sizes. A nanocomposite powder with a mean crystallite size of 35-40 nm was obtained after milling for 15 h.
