The internal load transfer and the deformation behaviour of aluminium–matrix composites reinforced with 2D-random alumina (Saffil ® ) short fibres was studied for different loading modes. The evolution of stress in the metallic matrix was measured by neutron diffraction during in situ uniaxial deformation tests. Tensile and compressive tests were performed with loading axis parallel or perpendicular to the 2D-reinforcement plane. The fibre stresses were computed based on force equilibrium considerations. The results are discussed in light of a model recently established by the co-authors for composites with visco-plastic matrix behaviour and extended to the case of plastic deformation in the present study. Based on that model, the evolution of internal stresses and the macroscopic stress–strain were simulated. Comparison between the experimental and computational results shows a qualitative agreement in all relevant aspects.