Formation and strengthening mechanisms of plate-shaped particles

Guest Speaker：Distinguished Professor Jian-Feng Nie，Monash University, Australia

Inviter: Prof. Guangyin Yuan

Date&Time: Tuesday, 14.Jan., 10:00-11:30

Venue: Meeting Room 216 , Building B,SMSE

Biography:

Jian-Feng Nie is a professor of the Department of Materials Science and Engineering at Monash University. His research interests cover magnesium alloys, aluminium alloys, biodegradable metals, precipitation and solid-solid phase transformations, applications of scanning transmission electron microscopy in materials characterization, and processing-microstructure-property relationships in metallic materials. His publications include a book, the 5th Edition of “Light Alloys”, a book chapter in the 5th Edition of “Physical Metallurgy”, an article on magnesium alloys in the 2nd Edition of “Encyclopedia of Condensed Matter Physics”, and over 150 papers on light alloys. 

Abstract:

Precipitation-hardened aluminium and magnesium alloys often contain nano-sized, plate-shaped precipitates of intermediate or equilibrium phases that form on rational planes of the matrix phase. Although it is well known that a higher number density of these nano-sized precipitates is crucial for enhancing alloy strength, the influence of their shape on strengthening is not as well recognized. Micro-alloying additions can alter the shape and distribution of these precipitate plates, but the exact formation mechanisms and the role of these micro-alloying elements in their formation remain debated. This presentation will focus on the mechanisms behind precipitate plate formation and strengthening models that incorporate the actual plate-shape of the particles. It will highlight that many of these precipitates, which are traditionally categorized as diffusional and non-displacive, actually possess a significant shear component in their formation, and contribute an extraordinary strengthening effect in comparison with non-spherical particles.