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Abstract: The TiB2 particulate reinforced magnesium matrix composites (MMCs) were fabricated by adding a TiB2–Al master alloy processed via self-propagating high-temperature synthesis (SHS) reaction of Al–Ti–B systems with the different molar ratio of Ti to B (n Ti:n B =1:2 and n Ti:n B =1:2.5, respectively) to molten magnesium and using the semisolid slurry stirring technique. When the molar ratio of Ti to B is 1:2 in TiB2–Al master alloy, the TiB2–Al master alloy and TiB2p/AZ91 composites contained a certain amount of transient TiAl3 phase; however, when the molar ratio of Ti to B is 1:2.5, the TiAl3 phase was almost completely eliminated and the distribution of TiB2 particulates generally appeared to be more homogeneous throughout the magnesium matrix. [Copyright &y& Elsevier]

Magnesium metal matrix composites (MMCs) reinforced with various fractions of 10, 15 and 20 vol.% B4C particulates fabricated by powder metallurgy (P/M) technique were investigated. Microstructure characterization of the composites revealed necklace distribution of B4C particulates in the matrix material and the presence of minimal micro-porosity. The X-ray diffraction (XRD) showed the formation of MgO and MgB2 in B4C/Mg composites. Moreover, the results revealed that the hardness and wear resistance of the composites were higher than those of as-cast Mg ingot and increased with increasing amount of B4C particulates from 10 to 20 vol.%. [Copyright &y& Elsevier]

The synthesis of in situ formed TiB2/Mg composite utilizing the self-propagating high-temperature synthesis (SHS) reaction that occurred between the molten magnesium and green preforms consisting of Al, Ti and B powders was investigated. The result shows that it is feasible that the smelting temperature of the magnesium matrix alloy is selected at 860 °C, which is slightly higher than the exothermic reaction temperature of 852 °C on the DTA curve, prepared for the SHS reaction in the Al–Ti–B system. An as-cast microstructure of the composite reveals a relatively uniform distribution of TiB2 particulates with hexagonal or rectangular size of ∼2.0 μm. Furthermore, an analysis of the powders extracted from the TiB2/Mg composite confirms that a small amount of blocky TiAl3 phase is also present in the composite. [Copyright &y& Elsevier]

The effect of Al content on the self-propagating high-temperature synthesis (SHS) reaction of the Al–Ti–C preform in molten magnesium was investigated. As the Al content in the preforms was increased over the range of 20–40 wt.%, the TiC particulate sizes decreased from ∼5.0 to ∼1.0 μm. Microstructural characterization of the TiC/Mg (AZ91D) composite showed relatively uniform distribution of TiC particulates in the matrix material and the presence of minimal micro-porosity. [Copyright &y& Elsevier]