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2014 年 01 月 27 日
Seminar - New Approaches to Surface Engineering and Grain Refinement of Metals, and the Future of Metal Research by Professor Mingxing Zhang

Date:   27 January 2014 (Monday)

Time:   11:00 am - 12:00 pm

Venue:  EF305, The Hong Kong Polytechnic University

Abstract:

Surface engineering is regarded as a major emerging technology that can effectively improve the surface durability of metallic materials, including wear resistance, corrosion and oxidation resistance, without significantly altering the properties of substrate. Cold spray is one of the most advanced techniques of surface treatment for metals. Using optimised cold spray processes developed at UQ, dense, uniform and highly bonded metallic or metal-based composite coatings can be produced on magnesium alloys, steels and any other metals. Such coating leads to dramatic increase in corrosion resistance to the level of stainless steels and improvement of wear resistance by 6 to 10 times compared with the substrate of AZ91 magnesium alloys at T6 condition. The coating also enables the use of plain carbon steels and ultrahigh strength steels as high strength stainless steels at lower cost. In this presentation, the bonding mechanism of cold spray will also be discussed.

Grain refinement concurrently increases yield strength, toughness and ductility of metals, thus it has been an active research topic for a few decades. The breakthrough progress in this area is the success in application of the edge-to-edge matching crystallographic model to understand the mechanism of grain refinement in cast metals and to the development of new and more effective grain refiners for magnesium alloys, zinc alloys and tin alloys. After briefly introducing the edge-to-edge matching model developed by M Zhang and his co-worker in the seminar, the most powerful grain refiners identified by the model and their efficiency in various cast metals will be presented. Then, the potential applications of the model to develop new and effective grain refiners for continuous casting and ingot casting of steels will be discussed. Such work aims to improve the quality of steel products through refining the grain size, decreasing porosity, eliminating macro-segregation, columnar structure, transverse cracks and improving mechanical properties.

Biosketch:

Professor Mingxing Zhang obtained his PhD degree in materials science and engineering at the University of Queensland in 1997. Since then, he has been working in the same institute as a Postdoctoral Research Fellow, Australian Research Council (ARC) – Australian Research Fellow (ARF), Senior Lecturer, Associate Professor and now a Professor. He is a world leading researcher in the areas of crystallography of phase transformations (he is the author of the well know edge-to-edge matching crystallographic model), grain refinement of cast metals and surface engineering of metals. His research expertise also includes physical metallurgy of steels and development of new alloy steels. In the last ten years he has obtained over $8.0 million research funding, published two patents and more than 160 papers in top international journals, including 18 in Acta Materialia (the top one journal in engineering materials with IF = 3.94) and one in Progress in Materials Science (IF = 23.2), with over 1500 citation. This leads to his h-index of 23. He is also a Key Reader for Metallurgical Materials Transactions A, an Editor for Advance in Materials Science and Engineering and a Topic Editor-in-Chief for World Journal of Engineering and Technology.