The defect evolution in shock loaded tantalum single crystals

Pang, Bo (2016). The defect evolution in shock loaded tantalum single crystals. University of Birmingham. Ph.D.

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Abstract

The defect structure of single crystal tantalum with orientation 001, 011 and 111 after a 6 GPa shock loading with lateral and back release waves were characterised using scanning electron microscopy (SEM) and transmission electron microscopy. The SEM images were filtered using ImageJ script to determine the type and fraction of deformation twins. A methodology of imaging dislocations in the tantalum single crystals using electron channelling contrast was made with the assistance of the dislocation contrast profile simulation based on the dynamical theory of electron diffraction. The dislocation density distribution was measured using electron channelling contrast imaging (ECCI) technique. The nucleation and growth of the deformation twins are discussed with the aid of finite element simulation of the wave propagation in the material. The defect evolution and response of the single crystals are found to be highly dependent on the loading orientation of the shock wave. The effects of the lateral release wave and back release waves on the deformation mechanisms are also discussed.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

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