Research Highlights

Metal alloys are versatile materials that can be tailored to exhibit desired properties. However, achieving both ultra-high strength and good ductility in these materials has been a long-standing challenge.

For example, established maraging processes can enhance alloy strength via precipitates. However, the presence of these precipitates also makes alloys brittle, limiting their ductility and therefore their applications where both strength and ductility are required.

In a 2023 article¹, Kim and coworkers from AIMR addressed this problem by developing a novel dual-phase medium-entropy alloy (MEA, Fe₆₈Ni₁₀Mn₁₀Co₁₀Ti_1.5Si_0.5 (at%)) with a strength of 1.6 GPa and ductility of ~25% using a maraging and reversion (M&R) process. The strategy used a new rapid low-temperature reversion method to engender both compositional and microstructural heterogeneities.

“Our M&R process generated both a core-shell configuration within the reversed austenite grains of the ferrous alloy, and a dual-phase microstructure containing a large fraction of metastable austenite” says Kim. “Respectively, these two heterogeneities enabled both the precipitation strengthening and the transformation-induced plasticity mechanisms simultaneously.”

By transcending the traditional strength-ductility trade-off that has long challenged the materials-science community, the team demonstrated a new pathway that utilizes chemical heterogeneity and metastable phase transformations for developing advanced structural materials with superior mechanical properties.

Currently, the team is expanding this approach to other MEAs and high-entropy alloys exploring how the versatile compositional landscape of these alloy systems can be leveraged to improve hydrogen storage performance as well as mechanical properties.

(Author: Patrick Han)