Mechanical alloying (MA) has been used to synthesize Ti 3 SiC 2 powder from the elemental Ti, Si, and C powders. The MA formation conditions of Ti 3 SiC 2 were strongly affected by the ball size for the conditions used. MA using large balls (20.6 mm in diameter) enhanced the formation of Ti 3 SiC 2 , probably via an MA-triggered combustion reaction, but the Ti 3 SiC 2 phase was not synthesized only by the MA process using small balls (12.7 mm in diameter). Fine powders containing 95.8 vol% Ti 3 SiC 2 can be obtained by annealing the mechanically alloyed powder at relatively low temperatures.

Mechanical alloying (MA) synthesis of Ti3SiC2 from a stoichiometric elemental powder mixture of Ti, Si, and C was conducted by using a planetary mill with a specially designed MA jar, which enables the real‐time measurement of temperature and gas pressure during the MA process. Sudden gas pressure and temperature rises were detected when the mixed powders were mechanically alloyed for a certain period, and consequently a large amount of Ti3SiC2 particles was synthesized. Using the Ti–Si–C system as an example, the present study confirmed the combustion reaction triggered by the ball‐milling process for the first time.

It is known that mechanical vibrations which applied during solidification affect microstructure refinement. However, it is not completely understood which factor of vibrations is important for microstructure refinement. Factors of vibrations are frequency, acceleration, velocity and amplitude. In this study, the effect of mechanical vibrations on microstructure refinement of Al-7 mass% Si alloys was investigated systematically. The mechanical vibrations were applied to the melt in an alumina crucible from about 923 K to 863 K, and the crucible was quenched in water at 863 K. As a result, it was found that the velocity of mechanical vibrations corresponding to the vibration energy is important factor for primary crystals refinement. The mechanical vibrations with high velocity regardless of frequency can refine the primary crystals. It is considered that the mechanical vibrations promote heterogeneous nucleation just below the liquidus temperature.

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