A microstructural investigation of stishovite-bearing quartzite from the Vredefort meteorite impact site in South Africa reveals features that are attributed to shock deformation. These include abundant mechanically induced Dauphiné twinning, rhombohedral deformation lamellae and associated residual stresses. Mechanical twins were identified with SEM-EBSD. Residual stresses are derived from equ...

advanced high strength steels (ahss) have recently attracted great attention because of their superior mechanical properties. a modern group of these steels, known as twinning induced plasticity (twip) steels, shows a unique combination of strength and ductility even at high rates of strain. in order to examine the functionality of such steels in dynamic loading conditions, their mechanical beh...

Large meteorite impacts cause great changes to geologic features on Earth, ranging from cratering and ejecta blankets to phase transformations in minerals. In this report we describe the effect of a shock wave on the crystallographic orientation of quartz crystals in quartzite from the Vredefort impact site in South Africa. Preferred orientation of bulk quartzite samples was measured by time-of...

Preferred orientation in granitic mylonites from the Santa Rosa mylonite zone in Southern California is investigated with time-of-flight neutron diffraction. Quartz and biotite display strong preferred orientation, whereas, feldspar alignment is weak. For quartz, a c-axis maximum in the intermediate fabric direction is consistent with dynamic recrystallization. Pole figures for positive and neg...

A comparative study of fracture in Al is carried out by using quantum mechanical and empirical atomistic description of atomic interaction at crack tip. The former is accomplished with the density functional theory (DFT) based Quasicontinuum method (QCDFT) and the latter with the original Quasicontinuum method (EAM-QC). Aside from quantitative differences, the two descriptions also yield qualit...

Diamond anvil cells (DAC) in radial synchrotron X-ray diffraction geometry were used to investigate texture development and identify deformation mechanisms in zinc and osmium at the Advanced Photon Source (APS) and the Advanced Light Source (ALS), respectively. Further experiments on cadmium and hafnium wires were carried out in the Deformation-DIA (D-DIA) multi-anvil press at APS to study the ...

In this work, plastic deformation was locally introduced at room temperature by nanoindentation on a γ-TiAl-based alloy. Comprehensive analyses of microstructures were performed before and after deformation. In particular, the Burgers vectors, the line directions, and the mechanical twinning systems were studied via accurate electron channeling contrast imaging. Accommodation of the deformation...

BACKGROUND Inequities in health have garnered international attention and are now addressed in Sustainable Development Goal 3 (SDG3), which seeks to 'promote well-being for all'. To attain this goal globally requires innovative approaches, one of which is twinning. According to the International Confederation of Midwives, twinning focusses on empowering professionals, who can subsequently be ch...