Damping properties of mechanically alloyed TiNi powders and Al/TiNi sintered materials

Microstructure and phase transformation of mechanically alloyed TiNi powders added to an aluminium matrix for enhancing the damping properties were studied. Four compositions between 48.5 and 51.5 at%Ti intermetallic compounds were selected to control the fraction of martensite phase of TiNi. Mechanically alloyed TiNi powders were heat-treated at a vacuum of 10(-6) torr for crystallization. Ball milled Al/TiNi composite powders were swaged at room temperature and rolled at 450 degrees C. After mechanical alloying for 10 yours, Ti and Ni elements were alloyed completely and an amorphous phase was formed. Amorphous phase was crystallized to martensite(B19') and austenite(B2) after heat treat for 1 hour at the temperature of 850 degrees C, and TiNi3 intermetallic compound was partially formed. A considerable amount of martensite phase remained after swaging and rolling the can of Al/TiNi composite. Specific Damping Capacity (SDC) increased as the Ti content increased. It was due to martensite amounts of TiNi particles. Few interfacial effects of the Al/TiNi phases on the damping properties were obtained.