Enhanced strength and ductility of metal composites with intragranularly dispersed reinforcements by additive manufacturing

Reinforcements in metal composites are usually dispersed at grain boundaries. We here show that the rapid solidification during laser additive manufacturing enables the spontaneous engulfment of reinforcing particles inside aluminum grains, which helps to decouple the stress concentration induced by grain boundaries and reinforcements. The additively manufactured TiB2-Al composite possesses 30% increase in tensile strength and nearly tripled ductility as compared with composite obtained by the traditional method. Our experimental investigations indicate that the intragranular dispersion of particles not only inhibits crack nucleation but also promotes strain hardening, leading to the remarkably enhanced mechanical properties. IMPACT STATEMENT Metal composite with intragranular dispersion of reinforcing particles can be achieved through additive manufacturing, which alleviates stress concentration and possesses much-improved ductility.