Fabrication of micro-fine spherical Ti–6Al–4V alloy powders based on hydrogen decrepitation and plasma spheroidisation

Abstract

A novel process was developed for scalable fabrication of micro-fine spherical Ti–6Al–4V alloy powders. The hydrogenation-treated Ti–6Al–4V alloy ingot was mechanically crushed into particles and then sieved into three size grades. The powders were separately sent through the radio frequency (RF) argon plasma system for spheroidisation. The fabrication process and powder characteristics were investigated. The results indicate the alloy ingot upon hydrogenation treatment can be efficiently crushed into fine particles with size of 5–76 μm. During RF plasma processing, the powders are found to be greatly refined due to hydrogen decrepitation with subsequent transformation into spherical morphology. The effect of hydrogen decrepitation on particle refinement is impaired with decreasing particle size of feed powders. The spherical powders exhibit a narrow particle size distribution and the average size is in the range of 8.2–27.9 μm. The spheroidised powders mainly consist of β-Ti and TiH_1.5.

Keywords:

• Ti–6Al–4V alloy
• Powder metallurgy
• Hydrogen decrepitation
• Plasma spheroidisation
• Powder characteristics

Additional information

Funding

This research was sponsored by the National Natural Science Foundation of China (No. 51204015), Aeronautical Science Foundation of China (No. 2013ZE74004) and the Fundamental Research Funds for the Central Universities (FRF-TP-14-095A2).