<p>In this study, the simultaneous effect of inoculation (Al–5Ti–B) and heat treatment (solutioned and aged) was studied on the functionally graded distribution of the Mg₂Si particles and mechanical properties along the radial direction of the Al-13.8 wt% Mg₂Si centrifugally cast cylinders. The chemical composition, microstructure and mechanical properties of the radial sectors were studied using energy dispersive X-ray (EDX) method, optical microscopy, hardness testing, and standard tensile testing, respectively. According to the results, due to resultant effects of the prevailing thermal regime and centrifugal force applied on the in situ formed particles during the solidification, the middle radial layer of the cast cylinder, compared with the outer and inner layers, showed a higher content of Ti as well as a higher volume fraction of the Mg₂Si particles. In addition, the hardness and tensile strengths of the Al–5Ti–B content aged cylinder in all radial sectors were considerably higher than those in other cylinders.</p>