Phase transformations are prevalent and play a profound role in energy density and rate capability in energy storage devices like batteries. Detecting the strain field at the nanoscale is one way to understand the phase transformation. Bragg Coherent diffractive imaging with phase retrieval algorithms is a possible candidate for imaging phase transformations. However, the current iterative algorithms fail to retrieve the images from X-ray data in the presence of large strains (~1%). By improving the phase retrieval algorithm, we show that Bragg coherent diffractive imaging of structural phase transformations in nanoparticles is possible. We verify our algorithm with reconstruction from simulated X-ray data.