A comparison of strengthening mechanisms in rolled and axisymmetrically deformed Ti-20Y composites

Two Ti-20%Y metal-metal composites were deformation processed: one axisymme trically and the other by rolling. The microstructures, preferred crystallo graphic orientations, and tensile strengths of each were measured periodica lly as the deformation progressed. The axisymmetrically deformed Ti matrix developed a [10 (1) over bar 0] fiber texture, and the rolled composite acq uired a texture with the [0001] tilted 31 degrees from the sheet normal tow ard the transverse direction with [10 (1) over bar 0] parallel to the rolli ng direction. The orientations of the {10 (1) over bar 10}[11 (2) over bar 0] and [0002][11 (2) over bar 0] slip systems in Ti with these textures wer e used in conjunction with the maximum possible slip distances for dislocat ion travel in each specimen to demonstrate that the axisymmetrically deform ed material should be stronger than the rolled material for composites of e qual phase thickness and spacing. The strengths of the two composites measu red in this study were compared at similar microstructural phase sizes and spacings, and the axisymmetrically deformed composite was indeed found to b e somewhat stronger, although the difference in strengths was not large. (C ) 1999 Kluwer Academic Publishers.