Fabrication of mechanically alloyed TiNiCu powders and damping properties of Al/TiNiCu sintered materials

The microstructure and phase transformation of mechanically alloyed Ti-(50-x)Ni-xCu powders added to an aluminium matrix to enhance their damping properties were studied. Four compositions between 5 and 20 at.%Cu intermetallic compounds were selected to control the fraction of the martensite phase of Ti-Ni-Cu. Mechanically alloyed Ti-Ni-Cu powders were heat-treated in a vacuum of 10(-6) torr for crystallization. Mechanically alloyed Ti-Ni-Cu powders were milled with Al, swaged at room temperature and rolled at 450 degrees C. After mechanical alloying for 10 hours, The Ti, Ni and Cu elements were completely alloyed and an amorphous phase was formed. The amorphous phase was crystallized to martensite (B19') and austenite (B2) after heat treatment for 1 hour at a temperature of 850 degrees C, and a Fe2Ti intermetallic compound was partially formed. As the Cu contents increased the austenite phase fraction increased. The specific damping capacity (SDC) of Al/TiNiCu composite was higher than that of the Al/TiNi composite or native aluminium.