(In,Ga)N alloy is a key material system for applications in optoelectronics and photovoltaics. Despite more than 20 years of research, a remaining central problem is the achievable In concentration in films grown with a high structural quality on GaN. One approach towards higher In concentrations is to reduce the lattice mismatch via growth on plastically relaxed InGaN buffers. In this project, we plan to study the dynamics of plastic relaxation in InGaN buffers by in-situ X-ray diffraction microscopy during annealing. This way, we aim to understand the peculiar dislocation patterns occurring in relaxed InGaN on GaN.