HIAF is a high-intensity heavy-ion accelerator complex, dedicated to interdisciplinary researches of nuclear physics,nuclear astrophysics, atomic physics, and heavy-ion applications for society. Its design, construction, and operation should rest on a strong partnership among the domestic and oversea institutions and companies.We hence call upon the expertise, aspirations, and resources of a host of collaborators.Various collaborations compromising scientists and engineers from universities, institutes, industries and companies are and will be established in order to do R&D on key accelerator techniques, design and fabricate prototypes of core devices, and develop new detectors and experimental methods. HIAF also enjoys a strong partnership with future users from domestic institutions and industries and nonprofits from around the world. HIAF users define the research programs and raise requirements, providing expert guidance to the HIAF Project team.