Predictive multiphase evolution in Al-containing high-entropy alloys

Abstract

The ability to predict and understand phases in high-entropy alloys (HEAs) is still being debated, and primarily true predictive capabilities derive from the known thermodynamics of materials. The present work demonstrates that prior work using high-throughput first-principles calculations may be further utilized to provide direct insight into the temperature- and composition-dependent phase evolution in HEAs, particularly Al-containing HEAs with a strengthening multiphase microstructure. Using a simple model with parameters derived from first-principles calculations, we reproduce the major features associated with Al-containing phases, demonstrating a generalizable approach for exploring potential phase evolution where little experimental data exists. Neutron scattering, in situ microscopy, and calorimetry measurements suggest that our high-throughput Monte Carlo technique captures both qualitative and quantitative features for both intermetallic phase formation and microstructure evolution at lower temperatures. This study provides a simple approach to guide HEA development, including ordered multi-phase HEAs, which may prove valuable for structural applications.

Irradiation‐Induced Extremes Create Hierarchical Face‐/Body‐Centered‐Cubic Phases in Nanostructured High Entropy Alloys

“…For example, the disordered body-centered-cubic (BCC) phase in the Al x CoCrFeNi HEA gradually transforms to an ordered B2 phase with decreasing temperature from 1200 °C. [24] Nonetheless, apart from the complex phase transformation involving intermetallics, the most common phase transformations have been observed between FCC and HCP phases. A simple difference in the stacking sequence of close-packed planes promotes reciprocal transformations through small atomic displacements.…”

Fundamental electronic structure and multiatomic bonding in 13 biocompatible high-entropy alloys

“…High-entropy alloys (HEAs) are complex metallic alloys [1][2][3][4] comprised of four, five, or more principal components of different concentrations. Such a structure leads to a high mixing entropy that favors the formation of single phase disordered solid solutions at higher temperatures 5,6 , although the enthalpy also plays a critical role in determining its composition and phase with no long-range-order (LRO) 1,7 . A significant amount of disorder exist in HEAs when they undergo elemental segregation, precipitation, and chemical ordering, but uncertainty remains regarding the existence and the nature of short-range-orders (SRO) 8 .…”

Tailoring heterogeneities in high-entropy alloys to promote strength–ductility synergy

“…Heterogeneities in HEAs. Figure 2 highlights new schemes of nanostructured heterogeneities 22,23,26,33,[36][37][38][39] . Our intent here is to call the readers' attention to the multilevel heterogeneities enabled by HEAs, and explain how they influence dislocation motion to elevate σ y to the gigapascal level, while boosting strain hardening and retaining ε u that rivals simple metals.…”