A DEVITRIFICATION STUDY OF MG-Y-SI-AL-O-N GLASSES

Non-isothermal kinetic parameters of devitrification for two glasses i n the Mg-Y-Si-Al-O-N system were determined by differential thermal an alysis. The substitution of oxygen by nitrogen in the anionic network, the cationic one remaining the same, results in a 80 kJ/mol increase of the apparent crystallization activation energy. Furthermore, the de termination of the Avrami exponent. whose value is close to 1.5 for ea ch glass. corresponds to a crystal growth probably controlled by a dif fusion process.