A lightweight strain-glass alloy showing nearly temperature-independent low modulus and high strength

Fast development of space technologies poses a strong demand for elastic materials that are lightweight, strong, but compliant to achieve high density of elastic energy storage, and such properties need to be temperature-insensitive in space environments^1-4. However, existing materials do not meet this demand. Here we report a lightweight magnesium-scandium (Mg-21.3 at. % Sc) alloy meeting this demand. It is as light and compliant as organic-based materials like bones and glass fiber reinforced plastics, but stronger than them^5-7; thus, it exhibits a record-high elastic energy density ~0.5 kJ/kg among various metallic and organic-based composite materials at a moderate stress level of 200 MPa^8,9. Importantly, the performance can persist for 1 million stress cycles and over a wide temperature range from ambient to cryogenic temperatures. Its exceptional properties stem from a strain-glass transition. In-situ microstructure observations during cooling show strain-glass nanodomains continuously form from the matrix phase, which enables low modulus, high strength, fatigue-resistance, and temperature-insensitivity. The lightweight strain-glass Mg-Sc alloy may find applications in space technologies and other fields such as orthopedics^1,9-11.