The boron carbide (B4C) titanium diboride (TiB2) ceramic eutectic is being investigated for armor and tribological applications. Electron diffraction shows [11 (2) over bar0] TiB2//[21 (3) over bar1] B4C//growth direction, (0001) TiB2//(1210) B4C is parallel to the interface plane, and transmission electron microscopy (TEM) imaging reveals no interface phase. Thermal residual stress distributions are calculated via finite element modeling of an experimental eutectic microstructure. The B4C matrix is found to be about 400 MPa in compression, and the TiB2 lamellae approximately 1.3 GPa in tension. Stress and strain energy concentrations are found at the tips of TiB2 lamellae. TEM of deformed materials correlates well with the finite element calculations, showing preferential fracture in areas of stress concentration. Interfacial delamination and crack deflection are also observed in deformed materials.