Atomistic Origin of Deformation Twinning in Biomineral Aragonite.
Deformation twinning rarely occurs in mineral materials which typically show brittle fracture. Surprisingly, it has recently been observed in the biomineral aragonite phase in nacre under high rate impact loading. In this Letter, the twinning tendency and the competition between fracture and deformation twinning were revealed by first principles calculations. The ratio of the unstable stacking fault energy and the stacking fault energy in orthorhombic aragonite is hitherto the highest in a broad range of metallic and oxide materials. The underlining physics for this high ratio is the multineighbor shared ionic bonds and the unique relaxation process during sliding in the aragonite structure. Overall, the unique deformation twining along with other highly coordinated deformation mechanisms synergistically work in the hierarchical structure of nacre, leading to the remarkable strengthening and toughening of nacre upon dynamic loading, and thus protecting the mother-of-pearl from predatory attacks.
Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing 48824, USA.
Jialin
J
Liu
State Key Laboratory for Powder Metallurgy, Central South University, Changsha, Hunan Province 410083, People's Republic of China.
Zaiwang
Z
Huang
Department of Mechanical Engineering, University of North Carolina at Charlotte, Charlotte, North Carolina 28223, USA.
Zhiliang
Z
Pan
Department of Mechanical Engineering, University of North Carolina at Charlotte, Charlotte, North Carolina 28223, USA.
Qiuming
Q
Wei
Deaprtment of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, Virginia 22904, USA.
Xiaodong
X
Li
Department of Chemical Engineering and Materials Science, Michigan State University, East Lansing 48824, USA.
Yue
Y
Qi