04 Compositions in the tantalum-carbon system were prepared by carburizing high-purity tantalum wires. T h e microstructures so produced exhibit regions of a characteristic striated structure identical to those observed by earlier investigators. There are disparities in the literature as to the origin of such structures in the tantalum-carbon system. They have been variously described as "twins," "striated structure," "precipitate," and' "structure of unknown origin." This paper presents

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... ive evidence that the structures in question are the result of precipitation on cooling. I n addition, a coherent precipitation model is applied in which it is shown that the lattice relationship { 0 0 0 1 )~~, c~~( 1 1 1 }~~~ can exist with less than 0.5% misfit. This relationship is shown to completely explain the