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AbstractÐA detailed description is given of the microstructure of the top layer of Ti±6Al±4V with SiC particles embedded with a high-power Nd:Yag laser system. Scanning electron microscopy (SEM), as well as conventional, analytical and high-resolution transmission electron microscopy (TEM) were used. An existing controversy about the presence or absence of Ti 3 SiC 2 in the reactive SiC/Ti systems is clari®ed and the ®rst observations of Ti 5 Si 3 precipitation on stacking faults in Si supersaturated TiC are reported. The Si released during the reaction SiC+Ti4TiC+Si results in the formation of Ti 5 Si 3 . If in the reaction layer regions in between the TiC grains become enclosed, the rejected Si content increases locally and Ti 3 SiC 2 plates with dominant (0001) facets nucleate. In the TiC grains particularly of the cellular reaction layer, a high density of widely extending stacking faults of the order of 100 nm is observed and on these faults in many instances small Ti 5 Si 3 precipitates are present. #

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Transmission electron microscopic observations were made of different dislocation structures in laser-nitrided titanium. Equidistant edge dislocations in the bulk and periodic surface structures exhibit a periodicity within the same order of magnitude. An analysis is presented in which both periodic phenomena are explained by cellular growth.