| The precipitation sequence and the variation with time and temperature in the growth rate of the rod-like aluminum nitride precipitate were investigated for an Fe-AI-N alloy. Using an extraction replica technique, face centered cubic aluminum nitride was observed at the initial stages of precipitation, and this later transformed into the rod-like hexagonal close packed aluminum nitride. The amount of aluminum nitride was closely related to the grain size; that is, the greater the amount of aluminum nitride, the smaller the grain size. The mean volume ratio of the precipitate is nearly proportional to the square root of the concentration product of aluminum and nitrogen contents. At a given temperature, the length of the rod-like precipitate was proportional to the holding time, and the diameter of the precipitate to the square root of the holding time. The orientation relationship between the rod-like aluminum nitride and the matrix has been determined by means of transmission electron microscopy. It gives (001)p∥(001)ｍ 〔001〕p∥〔2―10〕ｍ |
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