Effect of multi-layer structure molybdenum-silicon coating preparation on mechanical properties of additive manufacturing Ta10W alloy

The three-layer structure molybdenum-silicon high-temperature oxidation-resistant coating was prepared on selective laser melting Ta10W alloy by slurry sintering process. The microstructure and element distribution of the Ta10W alloy and coating were characterized by SEM and EDS. The tensile properties，microhardness of the Ta10W alloy and coating，and the coating bonding strength were tested. The results show that the coating of selective laser melting Ta10W alloy is divided into three layers: outer，sub-outer and inner layers. The outer layer is TaSi2 and MoSi2 phases，the sub-outer layer is TaSi2 phase and dispersed Ta5Si3 phase，and the inner layer is Ta5Si3 phase. The yield strength，tensile strength and uniform elongation of the coating and remove coating specimens are 639，647 MPa，13.6%，and 602 MPa，675 MPa，22.7%，respectively. Compared to the Ta10W alloy specimen，the uniform strain of the remove coating specimen is increased by 5.5%. The reason for this is that the thermal effect in the coating preparation process eliminates the residual stress of the Ta10W alloy formed by selective laser melting. The yield strength of the coated specimen is increased by 37 MPa due to the application of the coating. The microhardness of the outer layer，sub-outer layer，inner layer and Ta10W alloy were 550HV0.2，1120HV0.2 ，534HV0.01 and 307HV0.2，respectively. The average coating bonding strength is 63 MPa，which is higher than that of the ceramic and high entropy alloy coatings. This is due to the fact that the three-layer coating has a good metallurgical bond to the Ta10W alloy.