Micro-ultrasonic powder moulding of Sn–Bi/Cu composite micro parts in semisolid form

• Micro-UPM in a special semisolid forming was used to fabricate micro parts.
• The performances of micro parts were remarkable increased by alloying.
• The feasibility of micro-UPM in a special semisolid forming was verified.
• Forming mechanism of micro-UPM in a special semisolid forming was studied.

A mixture of Sn–Bi eutectic alloy powder, Cu powder and Cu fibre was used as raw material and semifinished micro parts were fabricated via micro-ultrasonic powder moulding (Micro-UPM) in a special semisolid form. The micro parts were obtained after sintering at 750 °C for 10 h and then cooling to room temperature in a furnace. The micro parts were investigated by DSC, metallographic analysis, XRD and tensile tests. The low-melting point Sn–Bi eutectic alloy was completely disappeared after the alloying treated with copper, which resulted in a remarkable increase in the thermal and mechanical properties of the micro parts.