| Based on the observation of interphase boundary precipitation(IBP) discussed in the first paper, the effort was devoted to characterize the sidewise growth of pearlite in terms of the ledge migration mechanism, which has been proposed especially for the edgewise growth of pearlite. Entire pearlite lamellae are parallel each other and their length is linearly changed within a colony. In additon, lamellar holes were observed at the starting points of the branching and the rows of IBP arrays were observed to be extended to the next lamellar plate through this lamellar holes. From these observations, it is proposed that the sidewise growth of pearlite does not occur through a random branching, but through a time-sequential branching via the laterai movement of growth ledges on pearlite-austenite interfaces. In contrast to the Hackeny and Shiflet`s edgewise growth model, this newly proposed growth model opearlite explains that the simultaneous growth of pearlite in sidewise and edgewise directions is achieved by the operation of the same growth Ledge migration. (Received January 6, 1995) |
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