Fibre-reinforced composites were produced by the modification of the static horizontal Bridgman method. The single-crystalline composite matrix consisted of the tetragonal T phase (Al 72 Cu 27 Co 1 ). Decagonal quasicrystal D phase (Al 64 Cu 20 Co 16 ) was the reinforcement in the form of fibres parallel to the solidification direction. These fibres were surrounded by the tetragonal Θ phase (Al 66 Cu 31 Co 3 ). The composite specimens in the shape of plates were studied by tensile tests and X-ray topography. The specimens deformed up to rupture and, from the X-ray topographs, the dependence of the composite structure defects on deformation was examined. It was found that the rupture of specimens is related to low-angle boundaries created during deformation. The influence of defects on the strength of the composites is discussed.