Fiber textures revisited

Abstract

The texture of model fiber composites containing a single drawn tungsten wire in a chemically vapor-deposited tungsten matrix is investigated spatially resolved by electron backscatter diffraction. The cylindrical symmetry of the model composites gives rise to different types of unique fiber textures. To obtain a proper texture classification, a concise analysis is necessary and classical descriptions of fiber textures are revisited. For the model composite, fiber texture types as cyclic ring fiber textures are discovered which have been postulated theoretically but never reported experimentally before. The matrix of the tungsten-fiber reinforced tungsten model composites shows a preferred alignment of 〈100〉 directions with the radial direction due to oriented growth and rotational symmetry about the growth direction giving rise to a cyclic 〈100〉 ring fiber texture. The drawn tungsten wires show strong alignment of 〈110〉 directions with the wire axis, in general indicating a central 〈110〉 fiber texture becoming broader towards the perimeter of the wire. A systematic inclination of the fiber axis occurs with increasing distance from the wire center resulting in a 〈110〉 single cone fiber texture. A weaker secondary alignment of 〈110〉 directions radially reveals the presence of a cyclic {110}〈110〉 fiber texture component. Additionally, frequent occurrence of twinning in body-centered cubic tungsten is observed: growth twins in the matrix constitute a separate cyclic 〈221〉 ring fiber texture component. Incidental twin orientation relationships are revealed abundantly in the wire. They are rationalized as being a pure geometrical consequence of the 〈110〉 fiber texture.