Non-Hookean large elastic deformation in bulk crystalline metals

Engineering metals often suffer from a small elastic deformation with a linear stress-strain relationship obeying Hooke's law. Here the authors observe a large nonlinear tensile elastic deformation with a strain of >4.3% in a bulk Cu alloy that offers potential for elastic strain engineering. Crystalline metals can have large theoretical elastic strain limits. However, a macroscopic block of conventional crystalline metals practically suffers a very limited elastic deformation of <0.5% with a linear stress-strain relationship obeying Hooke's law. Here, we report on the experimental observation of a large tensile elastic deformation with an elastic strain of >4.3% in a Cu-based single crystalline alloy at its bulk scale at room temperature. The large macroscopic elastic strain that originates from the reversible lattice strain of a single phase is demonstrated by in situ microstructure and neutron diffraction observations. Furthermore, the elastic reversible deformation, which is nonhysteretic and quasilinear, is associated with a pronounced elastic softening phenomenon. The increase in the stress gives rise to a reduced Young's modulus, unlike the traditional Hooke's law behaviour. The experimental discovery of a non-Hookean large elastic deformation offers the potential for the development of bulk crystalline metals as high-performance mechanical springs or for new applications via elastic strain engineering.

Automated summary

The authors observed a new copper alloy that can undergo a large nonlinear tensile elastic deformation at room temperature, offering potential for elastic strain engineering.