Laminated Mg-intermetallic composites were successfully fabricated by reaction synthesis in vacuum using 1 mm thick magnesium sheets and 0.25 mm thick copper foils. The final microstructure consisted of alternating layers of a hypoeutectic alloy containing crystals of CuMg₂ and eutectic mixture of CuMg₂ and solid solution of copper in magnesium and unreacted magnesium. The mechanical properties and fracture behavior of the fabricated composites were examined under different loading directions through compression, three-point bending and impact tests. The results indicated that the composites exhibited anisotropic features. The specimens compressed in the parallel direction failed by cracking along the layers of intermetallics and buckling of magnesium layers. The specimens compressed in the perpendicular direction failed by transverse cracking in the intermetallic layers and fallowing catastrophic cracking inclined about 45° to the interface of both intermetallic and magnesium layers. The flexural strength of the composites was higher in perpendicular than in parallel direction. When the load parallel to the layers was applied, the failure occurred by cleavage mode showing limited plastic deformation. When the load perpendicular to the layers was applied, the failure occurred by transverse cracking of the intermetallic layers and gradual cracking of the Mg layers. The Charpy-tested samples showed the same fracture behavior as the bend-tested specimens, which indicated that the same mechanisms operated at both high impact rate and low bending-test rate.

Reactive sintering of Al-Mg powder mixtures containing 5, 10, 15, and 20 wt.% Mg was used to synthesize lightweight composites reinforced with in-situ formed Al₃Mg₂ and Al₁₂Mg₁₇ intermetallics. Detailed microstructural investigation and phase analysis were employed to examine the phases in the composites formed at 400 and 450 ℃. The creation of particles with the Al₁₂Mg₁₇ cores encapsulated by the Al₃Mg₂ phase, which was further covered by a continuous aluminum matrix, was observed in the composites synthesized at 400 ℃. If the composites were held at 450 ℃, the liquid phase appeared at the Al-Mg interface, and as a result, a two-phase mixture was formed. It was the eutectic composed of the Al₃Mg₂ intermetallic compound and a solid solution of magnesium in aluminum (Al). The introduction of magnesium particles into the aluminum matrix resulted in a decrease in the density of composites, but there was no significant difference in the density of composites sintered at different temperatures. The mechanical behavior of the composites was examined using microhardness and hardness measurements and a room-temperature compression test. The result of using different cooling speeds, with the furnace and quenching in water, was the refining of the grains in the Al₃Mg₂ + (Al) eutectic, resulting in an increase in microhardness. The increase in hardness of the composites was related to the amount of particles introduced. Sintering at 450 ℃ and the cooling method influenced the hardness and compressive strength of the composites, which were higher by 10% and 13%, respectively, compared to composites sintered at 400 ℃. Tribological tests showed that introducing more and more magnesium particles into the aluminum matrix, followed by reactive sintering, increased the wear resistance. On the other hand, the sintering temperature and cooling conditions had little effect on the wear resistance of the Al-Mg composites.