Non-Hookean large elastic deformation in bulk crystalline metals

バルク単結晶銅系合金における非線形な巨大弾性ひずみ

Xu, S.*; 大平 拓実*; 佐藤 駿介*; Xu, X.*; 大森 俊洋*; Harjo, S.   ; 川崎 卓郎   ; Seiner, H.*; Zoubkov, K.*; 村上 恭和*; 貝沼 亮介*

Xu, S.*; Odaira, Takumi*; Sato, Shunsuke*; Xu, X.*; Omori, Toshihiro*; Harjo, S.; Kawasaki, Takuro; Seiner, H.*; Zoubkov, K.*; Murakami, Yasukazu*; Kainuma, Ryosuke*

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."