Direct nitridation of aluminum compacts in low temperature and pressured nitrogen atmosphere

Complete nitridation of aluminum compacts was achieved at temperatures from 580 to 600 degrees C (lower than the melting point of aluminum) and under a pressured nitrogen atmosphere of 1 and 4 MPa. The structure of the genera ted aluminum nitride compact was strongly dependent of reaction condition. In the case of preheating in low vacuum or reaction under a low nitrogen pr essure, a rather uniform structure was generated. On the other hand, in the case pre-heating in high vacuum and reaction under a high nitrogen pressur e, the generated structure consisted of three layers: two dense outer layer s and a porous inner layer. Melting of aluminum was not observed during nit ridation when the uniform structure was generated, which suggests that the nitridation proceeded as a solid-gas reaction.