Ni-AlxNiy core-shell structured particle reinforced aluminum based composites were fabricated using in-situ powder metallurgy method. Scanning electron microscope, X-ray diffraction, density analysis, hardness and compressive tests were used to investigate the effects of volume fraction of Ni particles and sintering atmosphere on the microstructures and mechanical properties of the composites. It has been shown that compared to Ar sintering atmosphere, N-2 atmosphere is active sintering atmosphere for fabricating the composites. The AIN formed during the sintering process, which can substantially increase the density and hardness of the composites. The strength of the composites sintered under N-2 atmosphere is higher than that of the composites sintered under Ar, while the ductility is slightly lower. It can be confirmed that the Ni-AlxNiy core shell structures are of great benefit not only to increase the strength but also to remain the plasticity of the composites. (C) 2015 Elsevier B.V. All rights reserved.