HEMI Seminar: J.F. Nie

Description

The Hopkins Extreme Materials Institute is pleased to welcome Dr. J.F. Nie, a professor of Materials Science and Engineering at Monash University, for a special seminar titled "Microstructures, Formability and Mechanical Properties of Wrought Mg Alloys."

Abstract:

Advances in manufacturing and processing technologies have stimulated renewed interest in lightweight magnesium alloys for applications in the automotive, communications and aerospace industries. Despite the emergence and the significance of Mg alloys as a class, their adoption in applications remains limited compared to that achieved for Al alloys. For commercial Mg extrusion alloys such as AZ31, they still suffer from a tension-compression yield strength asymmetry problem -- their yield strength under compression is much lower than that under tension. This problem is intimately related to the orientation of Mg grains in the extrudate. Similarly, such strong preferred grain orientations (basal texture) develop in Mg alloys during hot rolling, leading to non-uniform properties in Mg sheet. This strong basal texture is unfavorable and therefore considerable efforts have been made over the past decade to weaken it. At present, it is the accumulated empirical experience, rather than basic understanding, that provides the tools for practical design and development of magnesium wrought alloys. Attempts to improve the formability and mechanical properties of existing alloys, and to develop new alloys, have to date been restricted by a lack of fundamental understanding of microstructural factors that are most important in controlling the texture and deformation mechanisms. The microstructures of many thermomechanically processed Mg alloys have not been thoroughly characterised to allow the clear identification of the role of individual alloying elements in texture evolution and in basal texture weakening. This presentation will provide a review of our recent findings in the study of these issues associated with wrought magnesium alloys.