Microstructural evolution, strengthening and high thermal conductivity mechanisms of FeCrV-based medium-entropy alloys with Laves phase precipitation formed by adding minimal Ti

FeCrVTix medium-entropy alloys (MEAs) with BCC matrix and Laves precipitation have high yield strength (1097-1493 MPa), good fracture strain (27.1-47.7%) and excellent thermal conductivity (42.2-69.7 W/(m center dot K) at 673-1273 K), it is expected to be widely applied in the fields of advanced nuclear energy and aerospace. However, what is this kind of MEAs strengthening and high thermal conductivity mechanisms? According to the experimental results and theoretical calculations, a mixed-strengthening-mechanism model dominated by precipitation and fine-grain strengthening is proposed, it can well explain the increase in yield strength of FeCrV-based MEAs due to Ti-added. Meanwhile, the Laves-phase precipitation formed by adding Ti improves the compressive plastic deformation through grain refinement, crack bridging and crack deflection. Moreover, the high thermal conductivity of FeCrVTix MEAs is primarily due to the inelastic scattering of phonons and electrons in the medium/high-temperature regions. Based on the above mechanisms, the mechanical and thermal properties of MEAs/HEAs can be regulated in the pre-design and post-treatment stages, which provide new ideas and methods for the design and performance-optimization of high-performance structural materials.

Automated summary

A mixed-strengthening-mechanism model dominated by precipitation and fine-grain strengthening is proposed to explain the increase in yield strength of FeCrV-based MEAs due to Ti addition. The Laves-phase precipitation formed by adding Ti improves the compressive plastic deformation through grain refinement, crack bridging, and crack deflection in MEAs. Moreover, the high thermal conductivity of FeCrVTix MEAs primarily results from the inelastic scattering of phonons and electrons in the medium/high-temperature regions.