Speaker: 李秀艳研究员，中国科学院金属研究所

Inviter: 中国科学院数学院学术报告会组委

Title: Schwarz crystal: A different destination of grain refinement in metals

Language: Chinese

Time & Venue: 2026.09.11 10:40-11:50 数学院南楼N204（数学院交流报告会）

Abstract: The achievable grain sizes of metals have become smaller and smaller with the development of plastic deformation techniques. As the grain size is progressively refined to a few nanometers through straining, the structures of experimental metals evolve into Schwarz crystals instead of transforming into an amorphous structure as commonly believed. In this structure, the grain boundary network resembles a D-type three-dimensional periodic minimal surface. Copper with a Schwarz crystal structure remains stable against grain coarsening at temperatures close to the equilibrium melting point and exhibits high strength approaching the theoretical value. Al-Mg and Al-Zn alloys with extremely fine grains form stable supersaturated solid solutions with Schwarz crystal structures, in which atomic-diffusion-controlled processes including second-phase precipitation, Spinodal decomposition, grain coarsening and even melting are significantly suppressed. Neutron scattering and thermal transport measurements reveals an unusual phonon hardening and a quasilinear temperature dependence of thermal conductivity, which was previously only observed in low-dimensional materials.