Fracture modeling in heterogeneous materials poses significant challenges due to the complex interactions between material interfaces and crack propagation. The phase-field method for brittle fracture has emerged as an effective tool for simulating fracture in such materials. However, when applying this method to heterogeneous materials, computational difficulties can hinder its effectiveness as three major challenges arise. One significant drawback is that the width of the crack is determined by a length scale parameter, which requires using small finite elements around the crack. This requirement results in simulations that are computationally demanding. The energy functional of the phase-field fracture model is non-convex with respect to both field variables. Hence, monolithic solvers require special treatment. Consequently, a staggered iteration scheme is often employed; however, this approach exhibits deficiencies in numerical efficiency due to the substantial number of staggered iterations required during time steps involving crack phenomena. Furthermore, small time step sizes are essential to capture the propagation of fracture accurately. In this talk, we will adopt an efficient and robust approach to tackle these challenges of phase-field fracture simulations in particle-filled polymer composites. By integrating adaptive spatial refinement, a novel fracture energy-based convergence criterion, and adaptive temporal refinement and coarsening, we achieve significant performance improvements while maintaining physical accuracy. Our approach facilitates efficient simulation of fractures in a diverse range of particle-filled microstructures, varying in volume fraction and particle distribution. We will showcase applications across different configurations, demonstrating how our method effectively captures the influence of microstructural heterogeneities on crack initiation, propagation, arresting, and branching. These advancements provide valuable insights into the relationship between microstructure and microscopic fracture behavior.