Pressure-less Mg Melt Infiltration into Ti Powder Preform with Various Flow Channel Structures toward the Application to Binder Jetting Additive Manufacturing

Binder jetting (BJT), an additive manufacturing process, injects a binder into the powder bed to build up the green body. The green body undergoes sintering to obtain a dense product. However, the shrinkage during sintering makes it difficult to achieve a high dimensional accuracy. Pressure-less melt infiltration (PMI) is an alternative process that fills the pores of a preform with a metal melt spontaneously infiltrating by the capillary force. It becomes important to clarify how molten metal infiltrates and how defects form. This study investigates the mechanism of defect forming inside PMIed Mg/Ti composites by controlling the structure of Ti powder preforms. Different-sized (20-2300 m) Ti powders were pressed under various pressures (76-153 MPa) to fabricate preforms with various structures. It was found that gravity and gas pressure were key resistant forces for the capillary infiltration.