Mechanical alloying of fine structured Ti-Al-Nb aluminides involving Ti-hydride

Abstract

In order to produce high-quality aluminide alloys, a comparative study was carried out on the Mechanical Alloying (MA) characteristics of two powder mixtures, Ti-22Al-23Nb and TiH222Al-23Nb(at.%), respectively. It was noted that for the Ti-22Al-23Nb mixture MA led to the formation of a bcc (Nb,Ti,Al) solid solution with some degree of amorphisation under the experimental conditions. The use of Ti-hydride in the TiH2-22Al-23Nb mixture led to the formation of an amorphous (Nb,Ti,Al)H2solid solution. The presence of hydrogen in the powder mixture largely enhances the amorphisation process. TEM diffraction patterns confirmed the formation of both solid solutions. EDS analysis showed that chemical compositions of the bcc and of the amorphous solid solutions were close to the starting values.