Characterization of Cu6Sn5 intermetallic powders produced by water atomization and powder heat treatment

•The Cu6Sn5 intermetallic powder production route was proposed.•Single phase Cu6Sn5 powders could be by water atomization and heating.•Water-atomized Cu–Sn powders contained mixed Cu–Sn phases.•Solidification and heat treatment of water-atomized Cu–Sn powders are explained.

Since the Cu6Sn5 intermetallic shows its importance in industrial applications, the Cu6Sn5 intermetallic-containing powders, produced by a powder processing route with a high production rate, were characterized. The route consisted of water atomization of an alloy melt (Cu–61 wt.% Sn) and subsequent heat treatment of the water-atomized powders. Characterization of the water-atomized powders and their heated forms was conducted by using X-ray diffraction, scanning electron microscopy and transmission electron microscopy. Fine water-atomized powder microstructures consisted of primary hexagonal η-Cu6.25Sn5 dendrites coexisting with interdendritic η-Cu6.25Sn5 + β-Sn eutectic. Solidification of fine melt droplets was governed by surface nucleation and growth of the primary hexagonal η-Cu6.25Sn5 dendrites followed by η-Cu6.25Sn5 + β-Sn eutectic solidification of the remnant liquid. In coarse melt droplets, nucleation and growth of primary ε-Cu3Sn dendrites were followed by peritectic reaction (ε-Cu3Sn + liquid → η-Cu6.25Sn5) or direct crystallization of η-Cu6.25Sn5 phase from the undercooled melt. Finally, the η-Cu6.25Sn5 + β-Sn eutectic solidification of the remnant liquid occurred. Heating of the water-atomized powders at different temperatures resulted in microstructural homogenization. The water-atomized powders with mixed phases were transformed to powders with single monoclinic ή-Cu6Sn5 phase.