The synergy of computational micromechanics, metallurgy, and neutron diffraction can lead to key insights in understanding the deformation and failure mechanisms in advanced alloys, as well as material processing techniques. Several illustrative examples will be presented in this talk. Primarily, we focus on the fatigue behavior, which has been mostly investigated by ex situ microstructural characterizations and crack growth monitoring with replica techniques. The in situ, nondestructive neutron diffraction technique, together with the multiscale simulations, will provide us a linkage between the stress analyses (top-down point of view) to the failure mechanisms on inter- and intra-granular scales (bottom-up point of view). An irreversible, hysteretic cohesive interface model is developed to simulate a steady fatigue crack, which generates a continuum deformation history as inputs for the micromechanical analysis of lattice strain evolution. Comparisons with our neutron diffraction tests suggest the intergranular damage near the crack tip process zone be the dominant mechanism for fatigue crack growth.