Influence of the processing technique on the properties of NB-SI intermetallic composites for high-temperature applications processed by MIM and HIP

Nb-Si intermetallic composites feature high-temperature strength at rather low densities. This combination of properties offers a potential to replace nickel-based super alloys that are currently used for structural components of high-temperature applications, such as aircraft or land-based turbines. Previous studies revealed that Metal Injection Molding (MIM) of gas-atomized powder of the alloy composition Nb-20Si-23Ti-6Al-3Cr-4Hf (at.%) leads to a fine-grained microstructure with homogeneously distributed silicide particles. In this study, powder of the same alloy was processed by MIM as well as Hot Isostatic Pressing(HIP). Some of the sintered MIM samples were subjected to HIP for further densification. Results of all three processing techniques MIM, HIP and MIM+HIP were compared concerning residual porosity, microstructure, phase distribution and mechanical properties at ambient and elevated temperatures.