Preparation and Testing of Prototype Mg2Si-Mg-TiC and Mg2Si-TiC/TiB2 Composites

In this work, the preparation of various light-weight Mg-Mg2Si-TiC metal matrix composites and Mg2Si-TiC/TiB2 ceramic composites is described, and the influence of their structure on mechanical response is discussed. Mg-Mg2Si-TiC composites with continuous magnesium matrix densified to > 95% T.D. were fabricated by pressureless reactive infiltration of performs made from Mg2Si and TiC powders. Infiltration was performed in an argon atmosphere at temperatures 700°, 800°, and 900°C for 1 h. Trials made with Mg2Si preforms reinforced with TiB2 were unsuccessful. Mg2Si-TiC/TiB2 ceramic composites densified to > 97% T.D. were prepared by pressureless reactive sintering of tables made from Mg2Si and TiC or TiB2 powders. The reactive sintering was performed at 1020°C for 0.5–1 h under a protective argon atmosphere. The phases present in the obtained composite samples have been identified by scanning electron microscopy (SEM)/energy dispersive X-ray spectroscopy. In addition, room temperature tensile tests and hardness measurements (HV) were also undertaken. The results show that Mg-Mg2Si-TiC composites are with mechanical properties (Young modulus: 88–97 GPa, tensile strength: 186–197 MPa, hardness: 4.9–5.1 GPa, and fracture toughness: 6.4–6.5 MPa m1/2) superior to that of conventional magnesium alloys, while Mg2Si-TiC/TiB2 samples combined enhanced hardness (9–10 GPa) and fracture toughness (1.4–2.3 MPa m1/2) achieved in low density (2.2–2.5 g/cm3) composite structure.

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