Enhanced low-temperature sintering of Mo alloys with Cu-rich binders

Molybdenum (Mo) alloys, known for their exceptional physical and mechanical properties, find applications in aerospace, electronics, and medical fields. However, the high sintering temperatures and long processing times associated with their manufacturing lead to high-temperature furnace requirements and grain coarsening, negatively impacting their cost and mechanical properties. This study investigates the effect of sintering time on the liquid phase sintering (LPS) of Mo alloys containing 10 wt% Cu-rich binders sintered at 1300 °C. Thermodynamic calculations are used to find a suitable Cu-rich ternary binder composition to enhance the wettability of the liquid formed and Mo solubility while preventing the brittle intermetallic compound formation. The densification, microstructural evolution, and phase evolution in the sintered alloys are systematically investigated and correlated. Results revealed that the addition of Fe to the Cu-rich Cu-Ni binder and sintering at 1300 °C for 60 min prevented the formation of brittle intermetallic compounds and significantly improved sintered density (up to 99.2 % of theoretical density) and mechanical properties (Hardness = 342 HV). The sintered density and hardness values achieved in this study are comparable to or better than the reported values of other Mo alloys manufactured at higher sintering temperatures for longer sintering times. These findings demonstrate that the Cu-rich Cu-Ni-Fe ternary binder has a high potential for low-temperature manufacturing of dense, near-net-shaped and intermetallic-free Mo alloys with superior mechanical properties, offering a cost-effective alternative to conventional methods.