A domestic research team developed a light and strong titanium (titanium) medium-entropy alloy by leveraging atomic-level ordering. A medium-entropy alloy is an alloy that mixes several metallic materials in relatively equal proportions.
The National Research Foundation of Korea (NRF) said on the 23rd that a team led by Kim Hyeong-seop at Pohang University of Science and Technology POSTECH proposed a new alloy design method that integrates a medium-entropy alloy design strategy into titanium, and realized an alloy that simultaneously achieves light weight, high strength, and high elongation. The findings were published on the 7th (local time) in the international materials science journal Acta Materialia.
From everyday life to cutting-edge industries such as wearable devices, aircraft, and automobile parts, demand is rising for light and strong structural alloys, but conventional metallic materials have a limitation in which strength and elongation are inversely proportional.
To overcome this, convergence research is drawing attention on titanium alloys that can withstand high loads at low mass and on medium-entropy alloys that broaden the design space by mixing multiple elements in equal ratios. However, relying only on design strategies that search for new compositions had limits in developing titanium-based medium-entropy alloys with superior mechanical properties.
The researchers presented a new alloy design method that integrates distinct design approaches from titanium alloys and medium-entropy alloys to achieve light weight, high strength, and high elongation.
Analysis of the titanium medium-entropy alloy with a high-resolution transmission electron microscope capable of atomic-level observation and energy-dispersive spectroscopy showed that multiple principal elements underwent complex interactions within the alloy, forming a "short-range order." Short-range order refers to a state in which atoms are arranged randomly over large regions but exhibit certain regularity or arrangement at close range.
They also confirmed that this ordering increases the alloy's resistance to deformation and induces a work-hardening effect in which strength increases as the metal elongates. They were able to significantly secure the elongation value, which indicates how much a material can stretch before it breaks.
Kim Hyeong-seop said, "The new alloy material is expected to drive weight reduction of parts across various industries, including transportation, energy, and aerospace, contributing to improved fuel efficiency and reduced greenhouse gases," adding, "This study is a starting point for developing titanium medium-entropy alloys, and we will take on the challenge of developing ultra-high-strength titanium medium-entropy alloys by further utilizing multiple strengthening mechanisms."
References
Acta Materialia (2025), DOI: https://doi.org/10.1016/j.actamat.2025.121592