Investigating Composition Space in Medium and High Entropy Alloys Using a High-Throughput Synthesis Approach

The design of high entropy alloys often focuses on identifying near-equiatomic solid solution alloys; expanding these to include multiphase microstructures offers the opportunity to further enhance and control properties. Designing such multiphase, multi-principal element alloys (MPEAs) requires the ability to efficiently survey compositional space for phases and microstructures of interest using integrated experimental and computational methods. Guided by DFT and thermodynamic models of phase stability, our group applies a laser deposition-based synthesis method to rapidly produce alloy libraries with varying compositions. Processing parameters, including the laser power, travel speed, powder feed rate, and deposition order are varied, and their influence on the resulting microstructure and mechanical properties are assessed. This talk will focus on studies of the Nb-V-Zr-X system (X = Ti, Ta, Mo), which generally forms one or more BCC phases interspersed with intermetallic (Laves) phases. Compositional segregation and interphase boundary structures are examined in light of local measurements of mechanical behavior of the as-deposited and annealed materials. This work provides guidelines for predicting compositional effects on microstructure and properties, which will accelerate the design of MPEAs for high-temperature applications.