MoNbTi-based Refractory Multi-principal Element Alloy System: A Review of the Thermodynamic Phase Predictions, Formed Microstructures, and Mechanical Properties as a Function of the Fabrication Methods (AM versus SPS versus VAM)

Multi-principal element alloys (MPEAs), particularly those based on refractory compositions, have gained recognition for their suitability in extreme-environment applications such as nuclear reactors and aerospace due to their exceptional strength. This review aims to investigate the MoNbTi-based alloy system, including varied compositions with Zr, V, and Cr, and evaluate how different processing methods, namely additive manufacturing (AM), spark plasma sintering (SPS), and vacuum arc melting (VAM), impact the thermodynamic phase predictions, microstructure formation, and resulting mechanical properties. A comprehensive comparison of these processing routes sheds light on the influence of elemental composition on the development of solid-solution microstructures and their mechanical performances. The findings indicate that optimizing alloy composition and tailoring the processing method can significantly enhance the mechanical attributes and microstructural integrity of MPEAs, thus promoting their applicability in demanding conditions. Ultimately, this review contributes valuable insights into the effective design and processing of MoNbTi-based refractory alloys to achieve a desired balance of characteristics for advanced engineering applications.