Jian-Feng Nie

Abstract:

Grain boundaries play a critical role in plastic deformation and ultimately, in the control of mechanical properties and formability of magnesium alloys. Defects in such boundaries, especially segregated solute atoms, are often small in scale and their detection and characterization are beyond the capability of conventional electron microscopy techniques. Consequently, gaining fundamental insights into such defects has proved elusive. Advances in aberration-corrected scanning transmission electron microscopy (STEM), especially the techniques of high-angle annular dark-field STEM and energy-dispersive X-ray spectroscopy STEM, provide an opportunity to reveal the distribution and identity of solutes at the atomic scale. This presentation will review recent progress on the characterization of segregated solute atoms in the boundaries of some magnesium alloys. Implications of such observations on intelligent design for achieving improved properties will be discussed.