The structure and morphology of Ti–45Al composite powders treated by mechanical alloying

Abstract

In this study, Ti and Al elemental powders were used to prepare mixed powder by mechanical alloying. The morphology and phase compositions of mixed powders with different milling durations were investigated by scanning electron microscope, transmission electron microscope and X-ray diffraction. Experimental results show that powders are rapidly refined in the early stage of ball milling. However, during the process of milling, powder particle size reaches to a certain extent and change of particles size is minimal. Analyses show that intermetallic compounds, e.g. Ti₃Al, TiAl and TiAl₂, are synthesised in the composite powder during such high-energy milling process. A small amount of amorphous products are found in the 40 hours-milled powder. By high-energy ball milling, powder of Ti–45Al can be refined to nanoscale and synthesised intermetallic compounds. It is beneficial for the formation of sintered microstructure of fine and density. In this study, 40 hours-milled powder is found more suitable for following sintering.

Keywords:

• Ti–45Al composite powder
• High-energy milling
• Morphology
• Phase