The solid-state combustion synthesis of in-situ hybrid (Al3Ni+Al2O3)/Al composites and evaluation of its mechanical properties

In-situ hybrid (Al 3 Ni+Al 2 O 3 )/Al composites with bimodal size particles distributions were fabricated via an Al-NiO solid-state combustion reaction and subsequent hot extrusion process. The reaction system between Al and NiO was investigated by differential thermal analysis (DTA). The presence of Al 2 O 3 and Al 3 Ni in the matrix was verified by XRD/EDS analysis. The in-situ formed Al 3 Ni phase with varying morphologies and sizes such as particle, plate, strip and flake at different sintering temperatures were observed. And the exothermic reaction of Al-NiO can be reduced to below the melting point of Al, and the desirable sintering temperature was 600 ℃. In hot-extruded samples, both nano Al 2 O 3 and Al 3 Ni particles distributed homogeneously, and most of Al 3 Ni particles is smaller than 2 μm in size. When NiO content increases from 8% to 12%, Al matrix grains in composites can be refined from 1.7510 μm to 1.2050 μm. The mechanical properties of composites are enhanced significantly due to the introduction of Al 3 Ni and Al 2 O 3 particles, and can be up a YS of 322 MPa and a UTS of 407 MPa in the 15% NiO-Al composite. In addition, when the content of NiO increases from 10% to 12%, the strength of composites enhances without obvious sacrifice of EI. The strengthening and toughening mechanisms also was discussed in detail. • The solid-state combustion synthesis of in-situ (Al 3 Ni+Al 2 O 3 )/Al composites is feasible. • Most of Al 3 Ni particles is smaller than 2 μm in size. • The ratio of submicron Al 3 Ni particles (< 1μm) is beyond 60% in 10~15% NiO-Al composites. • The mechanical properties of composites are enhanced significantly. • When the NiO increases from 10% to 12%, the strength enhances without obvious sacrifice of EI.