Enhancement of Oxidation Resistance in Spark Plasma Sintered TZM Alloy through B₄C and Si Additions

TZM, a molybdenum-based alloy with a high melting point of 2620 °C, shows great potential for high-temperature structural applications. However, its susceptibility to oxidation limits its performance in air at elevated temperatures. We addressed this limitation by fabricating ceramic-metal-ceramic sandwich-type composites through spark plasma sintering at 1420 °C, using varying pressures (40-60 MPa) and holding times (5, 10, and 15 min). The sandwich structure comprises a middle layer of 95% TZM and 5% B₄C + Si, flanked by ceramic layers made of 90% B₄C and 10% Si. Investigations into these composites revealed key insights into their oxidation behavior, densification, microstructure, and mechanical properties. Notably, oxidation tests showed the formation of protective SiO₂ and Mo₂B layers on all samples. Among the tested conditions, the composite produced with a 10-minute holding time at 40 MPa exhibited the lowest specific mass loss at 1000 °C, achieving a 98.14% reduction compared to monolithic TZM.