Fig. 1. Geometry and size (mm) of samples: (a) for ex-situ tension tests; (b) for in-situ neutron diffraction.

Fig. 2. In-situ neutron diffraction experiment: (a) setup of experiment, where an extensometer was bound on the sample using two black rubber bands; (b) a neutron diffraction pattern.

Fig. 3. RVEs used for simulation of 3 vol.% CNT/2009Al composites: (a) all CNTs are modeled by generally aligned fibers, named as Fiber RVE; (b) 1.5 vol.% CNTs are modeled by aligned fibers and 1.5 vol.% CNTs are modeled by spheres, named as Fiber-Sphere RVE.

Fig. 4. Grain structure of the 2009Al alloy determined via EBSD.

Fig. 5. TEM images of the 3 vol.% CNT/2009Al composite: (a) grain structure; (b) CNT distribution.

Fig. 6. ODF results of the 2009Al alloy and the 3 vol.% CNT/2009Al composite.

Fig. 7. Macroscopic stress vs. strain curves: (a) as-recorded curves during in-situ neutron diffraction; (b) average stress-strain curves from in-situ experiments (S1?S4), the stress?strain curves from ex-situ experiments (N1 and N2), and the simulated curves.

Fig. 8. Comparison of work-hardening rate during plastic deformation as a function of true strain between the 2009Al-T4 sample N1 and the 3 vol.% CNT/2009Al-T4 sample N2.

Fig. 9. Lattice strain vs. applied strain curves of the 2009Al alloy and the 3 vol.% CNT/2009Al composite. Error bars of the measured lattice strains are shown for all curves.

Fig. 10. Evolution of lattice strains as a function of applied stress in both the 2009Al matrix of the composite and the 2009Al alloy: (a) {311} lattice strains, (b) {220} lattice strain, (c) {111} lattice strain and (d) {200} lattice strain.

Fig. 11. Load transfer mechanism in the 3 vol.% CNT/2009Al composite: (a) average stress in CNTs; (b) stress increment of the composite during elastic deformation stage.

Fig. 12. Average stress in the 2009Al matrix as a function of the applied strain.

Fig. 13. Predicted Mises stress (MPa) fields at the 0.7 % applied strain: (a) in the matrix and (b) the CNTs of the Fiber RVE; (c) in the matrix and (d) the CNTs of the Fiber-Sphere RVE. The tension loading direction is along the Y-axis, i.e. the vertical direction.

Fig. 14. Evolutions of FWHM: (a) instrumental FWHM at different scattering angles measured using a standard Si powder; (b) FWHM vs. applied strain curves of different materials; FWHM vs. applied stress curves of (c) the composite and (d) the alloy.