Amorphous alloys surpass E/10 strength limit at extreme strain rates

• Main Authors: Zhu, Wenqing, Li, Zhi, Shu, Hua, Gao, Huajian, Wei, Xiaoding
• Other Authors: School of Mechanical and Aerospace Engineering
• Format: Article
• Language: English
• Published: 2024
• Subjects: Engineering; Molecular analysis; Nucleation
• Online Access: https://hdl.handle.net/10356/174918
• Institution: Nanyang Technological University

Theoretical predictions of the ideal strength of materials range from E/30 to E/10 (E is Young's modulus). However, despite intense interest over the last decade, the value of the ideal strength achievable through experiments for metals remains a mystery. This study showcases the remarkable spall strength of Cu50Zr50 amorphous alloy that exceeds the E/10 limit at strain rates greater than 107 s-1 through laser-induced shock experiments. The material exhibits a spall strength of 11.5 GPa, approximately E/6 or 1/13 of its P-wave modulus, which sets a record for the elastic limit of metals. Electron microscopy and large-scale molecular dynamics simulations reveal that the primary failure mechanism at extreme strain rates is void nucleation and growth, rather than shear-banding. The rate dependence of material strength is explained by a void kinetic model controlled by surface energy. These findings help advance our understanding on the mechanical behavior of amorphous alloys under extreme strain rates.